Long-term Trends and Influencing Factors of Low Birth Weight in Hainan Island, China's Largest Free Trade Zone: A Retrospective Study from 2010 to 2021

Long-term Trends and Influencing Factors of Low Birth Weight in Hainan Island, China's Largest Free Trade Zone: A Retrospective Study from 2010 to 2021 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Long-term Trends and Influencing Factors of Low Birth Weight in Hainan Island, China's Largest Free Trade Zone: A Retrospective Study from 2010 to 2021 Ping-Hao Chen, Wei-Jia Wu, Bo-Wei Zhang, Xue-Lu Lei, Zhen-Ning Huang, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7302578/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background Low birth weight (LBW) poses substantial health risks for neonates and can have enduring consequences, such as higher healthcare costs and adverse effects on human capital and productivity. However, comprehensive epidemiological data on LBW in Hainan Province, China's Largest Free Trade Port and a strategically vital tropical region, remain strikingly limited. This study aims to assess the incidence of LBW in Hainan Free Trade Port and identify contributing risk factors. Methods This population-based retrospective cohort study analyzed 1,538,023 live births in Hainan Province from 2010 to 2021. Data on neonatal and parental demographics, clinical factors, and socioeconomic indicators were systematically collected. LBW, VLBW, and ELBW were classified based on birth weight. Spatial analysis used ArcGIS to assess geographic distribution. Temporal trends were analyzed via joinpoint regression. Multivariate binary logistic regression identified risk factors for LBW. Results The overall LBW incidence was 5.96%, with VLBW at 0.29% and ELBW at 0.02%. Joinpoint regression identified distinct temporal patterns; although the LBW rate remained stable from 2010–2015 (APC: -0.7209; 95% CI: -2.4331–1.0214; P = 0.3582), it increased significantly from 2015–2021(APC: 1.9190; 95% CI: 0.5875–3.2682; P = 0.0112). In contrast, both VLBW and ELBW showed sustained upward trends throughout the study period (APC = AAPC: 8.2298, 20.7718; 95% CI: 7.0264–9.4468, 15.1269–26.6934; both P < 0.0001). The geospatial analysis identified regional heterogeneity, with Wuzhishan exhibiting the highest LBW incidence (7.41%), and Haikou showing peak rates of VLBW (0.55%) and ELBW (0.06%). The occurrence of LBW, VLBW, and ELBW in Hainan Province was distributed in a follow-up manner. Multivariate binary logistic regression analysis demonstrated that parental age ( 35 years), minority ethnicity, preterm birth, multiple pregnancies, and delivery to a tertiary hospital were significantly associated with a higher risk of LBW. Conversely, male sex, post-term gestation, urban residency, higher regional GDP per capita, and a higher density of healthcare workers demonstrated significant protective effects against LBW. Conclusion There's a significant increase in LBW - related incidences in Hainan. Targeted prevention for high - risk groups is needed. Hainan Free Trade Port Low Birth Weight Retrospective Cohort Study Joinpoint Regression Figures Figure 1 Figure 2 1 Introduction Low birth weight (LBW) is defined as birth weight of < 2,500 grams. Common etiologies include preterm birth, intrauterine fetal growth restriction, or a combination of both 1 . A meta-analysis published in The Lancet reported a global LBW prevalence of 14.7% in 2020. South Asia had the highest prevalence at 24.4%, followed by sub-Saharan Africa at 13.9%. In contrast, North America, Australia, New Zealand, Central Asia, and Europe have lower prevalence rates, averaging 7.2% 1 . A national survey in China reported an LBW incidence of 7.21% 2 . Low birth weight reflects a multitude of public health issues and is closely associated with adverse perinatal outcomes, neonatal diseases, neonatal mortality, and child health problems 3 . It LBW is a significant predictor of neonatal and infant mortality and is associated with a higher risk of developing several chronic diseases in adulthood such as hypertension, type 2 diabetes, and coronary heart disease 4 . Additionally, LBW can affect neonatal growth and development, with adults born with LBW often experiencing a lower average height than their peers. Failure to achieve catch-up growth can adversely affect neurological and psychobehavioral development 5 . Moreover, LBW is closely associated with long-term social costs, as LBW infants often require specialized medical care, early intervention, and educational support, all of which place a significant burden on healthcare systems and social services 3 . The ripple effects of LBW reflect in increased health-care expenditures and may also manifest through potential reductions in human capital and productivity 6 , 7 , 8 . Consequently, understanding the incidence of LBW and its associated risk factors is crucial to protect infant health, improve public health standards, and foster social welfare and economic prosperity. It also presents a critical opportunity to implement population-wide preventive health strategies 3 , 9 . Hainan Island, located at China’s southernmost point and the nation’s largest free trade port, experienced profound socioeconomic changes following the introduction of the Hainan Free Trade Port policies. These transformations have led to significant talent migration, the optimization of industrial structures, sustained economic growth, and notable societal development. Against this backdrop, our research team, supported by a major science and technology initiative on the island, conducted a comprehensive study on the growth and development of children aged 0–18 years. This study established, for the first time, the standardized growth curves for this population. The comparison of the physical development indicators of children on Hainan Island with those from 35 years ago and against both Chinese and World Health Organization (WHO) standards revealed substantial improvements in the physical development of children in Hainan Island over the past three decades. However, these indicators still fall short of both national and international benchmarks. Longitudinal and cross-sectional analyses highlight persistent disparities; despite significant progress relative to historical data, the physical development on Hainan Island remains below the Chinese and WHO-based standards 10 . Preliminary studies have suggested that children on Hainan Island exhibit smaller statures than their domestic and international counterparts, raising concerns about whether they also experience higher LBW rates. Despite this, there is a lack of systematic research on the incidence and trends of LBW on Hainan Island. Therefore, this study aims to construct a retrospective birth cohort from 2010 to 2021 to analyze the incidence and temporal trends of LBW on Hainan Island and to identify the risk factors associated with LBW. The findings provide a scientific basis for the prevention and management of LBW on Hainan Island, fill the gap in epidemiological data on LBW in China's tropical and subtropical regions, and offer strategic recommendations for reducing the incidence of LBW and improving maternal and child health in the Hainan Free Trade Port, thereby supporting the successful implementation of China's "Universal Three-Child" policy. 2 Materials and methods 2.1 Study design This observational study utilized data from the Hainan Province Birth Certificate System (HPBCS), which includes birth information for infants and children born alive in the province between January 1, 2010, and December 31, 2021. The inclusion criteria for this study were as follows: (1) children born between January 1, 2010, and December 31, 2021, and (2) neonates who obtained their birth medical certificate for the first time. The exclusion criteria were as follows: (1) neonates with unclear sex information or birth weight, and (2) neonates of foreign nationality. 2.2 Ethics statement The study was conducted based on routinely collected health data from the Hainan Province Birth Certificate System without direct participation from the subjects. All data were anonymized to ensure that no personally identifiable information was included in the analysis. Because the data used in this study were encrypted and cannot be traced back to the individuals, informed consent was not required. The exemption from informed consent was approved by the Medical Ethics Committee of Hainan Women and Children’s Medical Center (Ethics Approval Number: HNWCMC Ethics Review No. [21] of 2025). 2.3 Data collection and quality control We collected relevant data on the neonates and their parents from the HPBCS database. Neonatal data included sex, residential location, gestational age, and birth weight. The parental data included parental age, ethnicity, multiple pregnancies, parity, and delivery at tertiary hospitals. Additionally, this study gathered data on the per capita gross domestic product (GDP) and number of healthcare workers in various counties and cities of Hainan from the 2010 to 2021 editions of the Hainan Statistical Yearbook. Established by the Hainan Provincial Health and Family Planning Commission, the HPBCS is managed by the Hainan Women and Children Medical Center, which permits the use of data from the system for medical research purposes. Birth information in the system is sourced from records registered by maternity institutions across the province. Quality control of birth data involves individual case verification during the entry of delivery information, validation when issuing birth medical certificates, and a three-tier quality control system for delivery registration information in the maternal and child health annual report. Each quality control level is overseen by designated personnel responsible for data collection, organization, review, and supervision. 2.4 Definitions The data of newborns included sex (male or female), residential location (urban or rural), gestational age (preterm, full term, or postterm), and birth weight. Additionally, parental information included age, ethnicity (Han or ethnic minority), multiple pregnancies, parity, and the level of the medical institution where the delivery occurred (whether it was a tertiary hospital). The classification of the residence, whether rural or urban, was determined based on the family’s address and categorized using the urban/rural code provided by the National Bureau of Statistics of China. According to the WHO guidelines, preterm births were defined as those occurring before 37 weeks of gestation; full-term births, 37–42 weeks; and, post-term births, after 42 weeks 11 . Multiple pregnancies were defined as those involving ≥ 2 fetuses in a single pregnancy. The National Health and Wellness Commission of the People's Republic of China classified hospitals as tertiary facilities based on their assessment criteria. The per capita GDP and number of healthcare personnel in various cities and counties in Hainan Province from 2010 to 2021 were divided into three levels based on the third percentile (low, middle, and high). Health personnel included medical, administrative, technical logistics, and other technical personnel. In line with the WHO standards 11 , newborns with a birth weight of < 2500 g were classified as LBW. Based on birth weight, newborns were further categorized into LBW (birth weight less than 2500 g), very low birth weight (VLBW, < 1500 g), and extremely low birth weight (ELBW, < 1000 g) groups. The LBW incidence rate was defined as the proportion of LBW newborns among all live births in a given year, calculated as follows: LBW incidence rate = (number of LBW newborns / number of live births) × 100%. 2.5 Statistical analysis The incidence rate distribution maps of LBW, VLBW, and ELBW for each prefecture-level city and county on Hainan Island were created using ArcGIS software (version 10.8.1), and the spatial autocorrelations of LBW, VLBW, and ELBW were calculated for each prefecture-level city and county in Hainan Island. Joinpoint regression analysis was conducted using Joinpoint 4.9.0.1 software, with the incidence of LBW, VLBW, and ELBW as the dependent variables and year as the independent variable. This analysis calculated the annual percentage change (APC) and the average annual percentage change (AAPC), with statistical significance assessed based on 95% confidence intervals (CI) 12 . Count data are presented as frequencies and percentages, and group comparisons were performed using the chi-square test. Univariate and multivariate unconditional binary logistic regression analyses were conducted to identify factors associated with LBW. First, crude odds ratios (OR) and 95% CI were calculated for each factor. Then, multivariate logistic regression was applied to estimate adjusted OR and their 95% CI. Analyses were performed using the SAS software (version 9.4; SAS Institute Inc., Cary, NC, USA). A P -value < 0.05 was considered statistically significant in a two-sided test. 3 Results 3.1 Baseline characteristics A total of 1538,023 newborns were included, of whom 838,775 (54.54%) were male neonates, and 737,686 (51.91%) were born in urban areas. Among the parents of these newborns, the ages of the parents was predominantly 25–34 years old, with 13,447,704 (87.43%) mothers aged 25–34 years and 13,447,704 (87.43%) fathers aged 25–34 years. In addition, parents were mostly of the Han nationality, with 1245,425 (80.98%) mothers and 1245,425 (80.98%) fathers of the Han nationality. The incidence of LBW infants on Hainan Island varied significantly across a number of population characteristics and environmental factors such as sex, residential location, parents‘ ethnic background, parents’ age, gestational week of delivery, number of maternal deliveries, level of medical institution, level of per capita GDP, and number of health care workers (all P < 0.05) (Table 1 ). Table 1 Demographic characteristics and related factors of live births and their parents in Hainan, 2010–2021 Variables Total Non-LBW LBW χ 2 P -value Total 1538023 (100) 1446350 (94.04) 91673 (5.96) Infant gender 2073.08 < 0.0001 Female 699248 (45.46) 650913 (93.09) 48335 (6.91) Male 838775 (54.54) 795437 (94.83) 43338 (5.17) Multiple pregnancy 95233.46 < 0.0001 No 1502871 (97.71) 1426834 (94.94) 76037 (5.06) Yes 35152 (2.29) 19516 (55.52) 15636 (44.48) Maternal age (years) 1414.71 < 0.0001 < 20 93740 (6.09) 86170 (91.92) 7570 (8.08) 25–34 1288991 (83.81) 1216122 (94.35) 72869 (5.65) ≥ 35 155292 (10.10) 144058 (92.77) 11234 (7.23) paternal age (years) 1049.94 < 0.0001 < 20 83424 (5.42) 76780 (92.04) 6644 (7.96) 25–34 1344704 (87.43) 1267642 (94.27) 77062 (5.73) ≥ 35 109895 (7.15) 101928 (92.75) 7967 (7.25) Mother Ethnicity 1045.29 < 0.0001 the Han nationality 1245425 (80.98) 1174918 (94.34) 70507 (5.66) ethnic minority 292598 (19.02) 271432 (92.77) 21166 (7.23) Father's ethnicity 1290.02 < 0.0001 the Han nationality 1293179 (84.08) 1219958 (94.34) 73221 (5.66) ethnic minority 244844 (15.92) 226392 (92.46) 18452 (7.54) Residential location 144.47 < 0.0001 Urban 737686 (51.91) 694353 (94.13) 43333 (5.87) Rural 683312 (48.09) 639871 (93.64) 43441 (6.36) Tertiary hospital 5654.93 < 0.0001 No 1287203 (83.69) 1218637 (94.67) 68566 (5.33) Yes 250820 (16.31) 227713 (90.79) 23107 (9.21) Gestational age 346662.00 < 0.0001 Preterm 86913 (5.65) 41821 (48.12) 45092 (51.88) Term 1426901 (92.78) 1380740 (96.76) 46161 (3.24) Over-term 24209 (1.57) 23789 (98.27) 420 (1.73) Parity 2966.69 < 0.0001 primiparity 781416 (50.81) 726845 (93.02) 54571 (6.98) multiparity 756607 (49.19) 719505 (95.10) 37102 (4.90) GDP 431.17 < 0.0001 Low 511057 (33.23) 483255 (94.56) 27802 (5.44) Middle 511391 (33.25) 480526 (93.96) 30865 (6.04) High 515575 (33.52) 482569 (93.60) 33006 (6.40) Health personnel 1323.52 < 0.0001 Low 509178 (33.11) 481245 (94.51) 27933 (5.49) Middle 516028 (33.55) 487889 (94.55) 28139 (5.45) High 512817 (33.34) 477216 (93.06) 35601 (6.94) In particular, the incidence of LBW was higher among girls than boys (6.91% vs. 5.17%). The prevalence of LBW was higher among children in rural areas than in urban areas (6.36% vs. 5.87%). The incidence of LBW babies was higher among newborns whose parents’ ethnic background was ethnic minority than among those whose parents’ ethnic background was the Han nationality (mother's ethnic background: 7.23% vs. 5.66%; father's ethnic background: 7.54% vs. 5.66%). The incidence of LBW was higher in newborns with parents aged 35 years (mother's age: 8.08% vs. 5.65% vs. 7.23% ; father's age: 7.96% vs. 5.73% vs. 7.25%). The incidence of LBW in multiple pregnancies was significantly higher than that in singleton pregnancies (44.48% vs. 5.06%). The incidence of LBW babies was significantly higher in preterm babies than those in term and expired neonates (51.88%, 3.23% vs. 1.73%). The incidence of LBW babies was higher among primiparous women than that in multiparous women (6.98% vs. 4.90%). In terms of the level of medical institution, the incidence of LBW babies was higher for newborns delivered at tertiary hospitals than in non-tertiary hospitals (9.21% vs. 5.33%). In terms of economic level, the incidence of LBW babies was higher in areas with high GDP per capita than in areas with low and medium GDP per capita (6.40% vs. 6.04% vs. 5.44%). In terms of health care resources, the incidence of LBW was higher in areas with a higher number of health care workers than in areas with a low and medium numbers of health care workers (6.94% vs. 5.45% vs. 5.49%). 3.2 Incidence rate and changes in low birth weight infants in Hainan Island from 2010 to 2021 An analysis of LBW incidence from January 1, 2010, to December 31, 2021, in Hainan Province revealed an overall LBW incidence of 5.96%, with VLBW at 0.29% and ELBW at 0.02%. Among the 18 prefecture-level cities and counties in Hainan (excluding Sansha City), Wuzhishan City had the highest incidence rate of LBW at 7.41%, whereas Haikou City had the highest incidence rates of VLBW at 0.55% and ELBW at 0.06% ( P < 0.0001). Spatial autocorrelation analysis revealed that the occurrences of LBW, VLBW, and ELBW infants on Hainan Island did not exhibit spatial autocorrelation and that they were randomly distributed. (Fig. 1 ). In 2010, the incidence rates of LBW, VLBW, and ELBW in Hainan Province were 5.96%, 0.19%, and 0.01%, respectively. By 2021, these rates had risen to 6.61%, 0.48%, and 0.07%, respectively (Fig. 2 ). Joinpoint regression analysis indicated no significant changes in the incidence of LBW between 2010 and 2015 (APC = -0.7209, 95% CI: -2.4331-1.0214, P = 0.3582). However, from 2015 to 2021, a significant increase in LBW incidence was observed (APC = 1.9190, 95% CI: 0.5875–3.2682, P = 0.0112). Over the period from 2010 to 2021, the VLBW incidence in Hainan showed no distinct joinpoints but exhibited a consistent increase (APC = AAPC = 8.2298, 95% CI: 7.0264–9.4468, P < 0.0001). Similarly, the incidence of ELBW demonstrated a notable upward trend (APC = AAPC = 20.7718, 95% CI: 15.1269–26.6934, P < 0.0001) (Table 2 ). Table 2 APC and AAPC of low birth weight incidence rate in Hainan, China, 2010–2021. Type Year Annual percentage change Average annual percent change APC (95%CI) t P AAPC (95%CI) t P LBW 2010–2015 -0.7209(-2.4331-1.0214) -0.9834 0.3582 0.7105(-0.1768-1.6057) 1.5680 0.1169 2015–2021 1.9190(0.5875–3.2682) 3.1479 0.0112 VLBW 2010–2021 8.2298(7.0264–9.4468) 15.7595 <0.0001 8.2298(7.0264–9.4468) 15.7595 <0.0001 ELBW 2010–2021 20.7718(15.1269–26.6934) 8.7851 <0.0001 20.7718(15.1269–26.6934) 8.7851 <0.0001 APC:Annual percentage change; AAPC:Average annual percent change. 3.3 Identification of significant risk factors Multivariate logistic regression analysis identified several risk factors for LBW in Hainan Island, including parents aged 35 years (AOR = 1.213,1.049; 95% CI:1.172–1.255, 1.019–1.081; P < 0.0001, 0.0015), prematurity (AOR = 27.726; 95% CI: 27.233–28.228; P < 0.0001), multiple pregnancies (AOR = 7.669; 95% CI: 7.441–7.904; P < 0.0001), primiparity (AOR = 1.435; 95% CI: 1.411–1.459; P < 0.0001), parents belonging to an ethnic minority (AOR = 1.128, 1.313; 95% CI: 1.101–1.155, 1.280–1.347; P < 0.0001, < 0.0001), and delivery in a tertiary medical institution (AOR = 1.246; 95% CI: 1.218–1.275; P < 0.0001). In contrast, prolonged pregnancy (AOR = 0.522; 95% CI: 0.472–0.577; P < 0.0001), male sex (AOR = 0.628; 95% CI: 0.617–0.638; P < 0.0001), urban residence (AOR = 0.805; 95% CI: 0.792–0.818; P < 0.0001), areas with higher GDP per capita (AOR = 0.903; 95% CI: 0.880–0.927; P < 0.0001), and areas with a higher number of health care workers (AOR = 0.955; 95% CI: 0.930–0.981; P < 0.0001) were protective factors against LBW. (Table 3 ). Table 3 .Multiple logistic regression analysis of risk factors for low birth weight in Hainan, China 2010–2021. Variables LBW LBW B UOR 95% CI P B AOR 95% CI P Infant gender Female -0.310 0.734 0.724–0.744 < 0.0001 -0.466 0.628 0.617–0.638 < 0.0001 Male 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Multiple pregnancy No 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Yes 2.710 15.034 14.703–15.373 < 0.0001 2.039 7.686 7.457–7.922 < 0.0001 Maternal age < 20 0.383 1.466 1.430–1.503 < 0.0001 0.193 1.213 1.172–1.255 < 0.0001 25–34 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) ≥ 35 0.264 1.301 1.275–1.329 < 0.0001 0.048 1.049 1.019–1.081 0.0015 paternal age < 20 0.353 1.423 1.387–1.461 < 0.0001 0.179 1.196 1.153–1.239 < 0.0001 25–34 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) ≥ 35 0.251 1.286 1.255–1.317 < 0.0001 0.102 1.108 1.071–1.146 < 0.0001 Mother Ethnicity the Han nationality 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) ethnic minority 0.262 1.300 1.279–1.321 < 0.0001 0.120 1.128 1.101–1.155 < 0.0001 Father's ethnicity the Han nationality 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) ethnic minority 0.306 1.358 1.336–1.381 < 0.0001 0.272 1.313 1.280–1.347 < 0.0001 Residential location Urban -0.084 0.919 0.907–0.932 < 0.0001 -0.217 0.805 0.792–0.818 < 0.0001 Rural 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Tertiary hospital Yes 0.590 1.804 1.776–1.832 < 0.0001 0.220 1.246 1.218–1.275 < 0.0001 No 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Gestational age Preterm 3.473 32.242 31.723–32.769 < 0.0001 3.322 27.726 27.233–28.228 < 0.0001 Term 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Over-term -0.638 0.529 0.480–0.582 < 0.0001 -0.650 0.522 0.472–0.577 < 0.0001 Parity Primiparous 0.375 1.455 1.436–1.476 < 0.0001 0.361 1.435 1.411–1.459 < 0.0001 multiparous 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) GDP Low 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Middle 0.110 1.116 1.098–1.135 < 0.0001 0.036 1.036 1.013–1.060 0.0023 High 0.173 1.189 1.169–1.209 < 0.0001 -0.102 0.903 0.880–0.927 < 0.0001 Health personnel Low 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) 1 (ref) Middle -0.006 0.994 0.977–1.011 0.454 -0.025 0.975 0.952–0.998 0.0311 High 0.251 1.285 1.265–1.306 < 0.0001 -0.046 0.955 0.930–0.981 0.0008 All odds ratios were mutually adjusted for other variables in the table. UOR:Un-adjusted odds Ratio.AOR:Adjusted odds Ratio. 4 Discussion This study, the first to comprehensively analyze LBW, VLBW, and ELBW epidemiology in Hainan using 2010–2021 data, reveals that pre-2015 LBW incidence was 5.96%, with lower rates for VLBW and ELBW. Post-2015 saw a significant LBW increase, while VLBW and ELBW continued their upward trends. Geospatial analysis shows Wuzhishan City had the highest LBW rate, and Haikou the highest VLBW and ELBW rates, with no spatial autocorrelation observed. Key risk factors for LBW included preterm birth, multiple pregnancies, primiparity, minority ethnicity, and delivery in tertiary institutions. Protective factors comprised post-term pregnancy, male sex, urban residence, higher regional GDP, and more healthcare workers. These findings offer crucial evidence for shaping maternal and child health policies in Hainan. Between 2010 and 2021, the overall LBW incidence in Hainan Island was 5.96%. These rate is lower than those reported in the United Kingdom (6.8%), Portugal (8.9%), Spain (7.5%), Greece (9.9%), the United States (8.3%), South Korea (6.6%), Japan (9.4%), and several African nations (10.0–15.7%) as well as the national average in China (7.21%) 2,13 . Compared to other regions in mainland China, the LBW incidence in Hainan Island was higher than in Beijing (4.23%) 14 , Chongqing (1.7%) 15 , and Inner Mongolia Autonomous Region (2.7%) 16 , but lower than that in Guangxi Province (8.05%) 17 . The variation in LBW incidence across regions can be attributed to a combination of factors including socio-political policies, social welfare systems, healthcare service coverage, public health infrastructure, and demographic characteristics. Collectively, these factors influence maternal health and prenatal care quality, thereby affecting the incidence of LBW in newborns 18 , 19 . In Hainan Island, Wuzhishan City exhibited a relatively high incidence of LBW, whereas Haikou City was characterized by higher rates of VLBW and ELBW. The results showed that Wuzhishan City exhibited a relatively high incidence of LBW (7.41%), possibly due to its geographical location, economic development, and distribution of medical resources. Located in the central region of Hainan Island, Wuzhishan is at a high altitude and has a large ethnic minority population. Its mountainous terrain limits transportation and economic development and contributes to the relative scarcity of medical resources. In contrast, Haikou City had higher rates of VLBW (0.55%) and ELBW (0.06%). As the provincial capital with abundant high-quality medical resources, Haikou City is equipped to provide advanced diagnostic and treatment services to critically ill pregnant women, which may facilitate the survival of more VLBW and ELBW infants. The Hainan provincial government has recognized these challenges and is actively implementing measures to enhance maternal and child health. Joinpoint regression analysis results indicated that from 2010 to 2015, the incidence of LBW in Hainan Island remained stable, with no significant upward or downward trends. However, from 2015 to 2021, an upward trend was observed, with the LBW rate reaching 6.61% by 2021. This increase may be attributed to factors such as changes in fertility policies, the widespread adoption of assisted reproductive technology, and environmental and climatic influences. Since the introduction of the "one couple, two children if one is an only child" policy in 2013, followed by the "universal two-child" policy in 2016 and the "three-child policy" in 2021, China's successive relaxation of fertility policies has likely encouraged more older parents to have children 15 , 20 . However, advanced maternal age is associated with a higher risk of maternal comorbidities (e.g., gestational hypertension and diabetes) and obstetric complications (e.g., miscarriage, preterm birth, and fetal growth restriction), all of which are established risk factors for LBW 15 , 21 , 22 . Additionally, paternal age should not be overlooked because it can affect offspring birth outcomes by influencing sperm epigenetics characterized by increased methylation, DNA fragmentation, telomere elongation, mutations, and genomic instability 23 , 24 . Climate change, along with the continued reliance on fossil fuels, has led to higher levels of PM 2.5 and ozone in the atmosphere, which are linked to a higher risk of LBW 25 . Additionally, with the expanding use of assisted reproductive technologies and their markedly enhanced success rates, epidemiological studies have demonstrated a corresponding increase in the incidence of LBW among assisted reproductive technology-conceived offspring 26 , 27 . Between 2010 and 2021, the incidence of ELBW and VLBW infants in Hainan Island showed an increasing trend (both P < 0.05). However, the Birth Certificate System in Hainan Province meticulously records data of surviving newborns, indirectly reflecting the increasing survival rates of ELBW and VLBW infants in the region. This trend may be attributed to advancements in clinical rescue techniques, improvements in prenatal and perinatal healthcare, and enactment and enforcement of national policies, all of which have contributed to a general reduction in the mortality rates of ELBW and VLBW infants 28 . The multivariate logistic regression analysis revealed that preterm birth, multiple gestation, primiparity, parents aged 35 years, ethnic minority background status of parents, and delivery at tertiary hospitals were significant risk factors for LBW in Hainan Island. Preterm birth exhibited the highest risk ratio among these factors, aligning with previous studies 29 . This is primarily because birth weight is largely determined by the duration of pregnancy and fetal growth rate 30 . The later stages of pregnancy, particularly between 28 and 36 weeks of gestation, are crucial for rapid fetal growth. Preterm birth reduces the time available for fetal development in utero, thereby significantly affecting birth weight. Thus, the early identification and proper management of gynecological, obstetric, or other systemic conditions that may lead to preterm birth are essential for maximizing fetal development and reducing the incidence of LBW. Multiple pregnancies increased the risk of LBW, which is consistent with prior research 31 . This higher risk can be attributed to the higher likelihood of pregnancy complications, such as hypertension, intrauterine growth restriction, and placental abruption, which are common in multiple pregnancies 31 .These conditions often lead to preterm birth, subsequently affecting birth weight. This phenomenon may also be attributed to the fact that the critical physiological resources essential for fetal development are competitively allocated between twin fetuses during multifetal pregnancies 32 , 33 . Although multiple pregnancies are not modifiable factors for reducing the LBW incidence, the identification and effective management of health conditions in women with multiple pregnancies play a significant role in mitigating the risk of LBW. Parity is an important predictor of LBW in neonates. Primiparous women have a higher risk of delivering LBW infants 34 , 35 . The results of this study also support this notion, with primiparous women having a 1.435-fold higher risk of LBW than multiparous women. Hinkle et al 35 . found that the relationship between birth weight and parity was nonlinear, with birth weight increasing incrementally with increasing parity and stabilizing between the fourth and seventh deliveries. This phenomenon may be related to physiological changes that promote fetal growth during pregnancy and are not fully reversed postpartum, thereby creating a more effective foundation for subsequent pregnancies 36 , 37 . In particular, compared with that in a non-pregnant uterus, the uteroplacental blood flow responsible for delivering oxygen and nutrients to the fetus is greater in subsequent pregnancies 38 , 39 . Additionally, structural factors may limit uterine capacity during the first pregnancy, whereas the size and protein content of the uterus increase correspondingly with increasing parity 36 , 40 . Firstborn infants may be exposed to a distinct maternal immune environment compared to that in subsequent pregnancies, which may result in relatively restricted growth 35 . Although the incidence of LBW deliveries is higher among multiparous women than that among primiparous women, this may be more closely related to the high parity associated with a history of abortions 41 , 42 . Therefore, the findings suggest that, following the relaxation of fertility policies in China, the impact of increased parity on the incidence of LBW may be relatively minor. Compared to parents aged 25–34 years, those aged 35 years were at an increased risk of LBW. Consistent with previous research findings 15 , the risk of LBW infants among young pregnant women is significantly higher, which may be closely related to the following factors: inadequately developed and matured physiological functions of the mother, relatively low cultural and educational levels; poor economic status, and lack of comprehensiveness in prenatal care measures 43 , 44 , 45 . In addition, the biological impact of paternal age on birth outcomes stems from the fact that gene expression of the father's genes in the placenta is higher, and compared to mature and older men, there is a greater likelihood of mutations in these genes in younger and less mature men 34 . Advanced maternal age is associated with a higher incidence of pregnancy comorbidities (such as hypertension and diabetes) and a significant increase in the occurrence of pregnancy complications (such as miscarriage, preterm birth, placenta previa, stillbirth, and fetal growth restriction), which, in turn, leads to an increased risk of LBW 21 , 22 . In fathers, advanced age can exert epigenetic effects on the sperm, which are characterized by increased sperm DNA methylation, DNA fragmentation, telomere shortening, increased mutations, and reduced overall genomic stability 23 , 24 . These changes make advanced paternal age an important factor influencing offspring birth outcomes and may further increase the risk of LBW. In this study, an ethnic minority status was associated with a higher risk of LBW, consistent with previous research. This may be linked to the lower socioeconomic status in areas where ethnic minorities are concentrated in Hainan. Mothers from impoverished families are more likely to give birth to LBW infants compared to those from wealthier families, primarily because of inadequate access to good nutrition and prenatal care 46 , 47 . Moreover, factors such as poverty, discrimination, and low education levels increase the risk of preterm birth or intrauterine growth restriction in minority populations, which in turn contribute to LBW 47 , 48 . In ethnic minority-inhabited regions, it is crucial to increase economic support, improve nutritional and medical conditions, provide personalized healthcare services, eliminate discrimination, and safeguard fair rights and interests, all of which aim to reduce the risk of low birth weight occurrence. The study also revealed that delivery at a tertiary medical institution was an independent risk factor for LBW. Tertiary hospitals, the highest-level healthcare units, offer advanced medical facilities and diagnostic technologies, which make them the primary providers for high-risk pregnancies. Consequently, a higher proportion of pregnancy-related complications are managed in these institutions, leading to a higher incidence of LBW infants in these settings 49 . Conversely, post-term pregnancy, male sex of the neonate, urban residence, regions with higher per capita GDP, and areas with a greater number of health workers are protective factors against LBW in Hainan. Postterm pregnancy reduced the risk of LBW, which may indirectly decrease the risk of LBW infants by increasing the risk of macrosomia 50 . This study showed that female sex of the infant is a risk factor for developing small for gestational age infants, which is consistent with relevant research results. This phenomenon may be related to biological differences in fetal sex, as there are differences in antigen or androgen levels between fetuses of different sexes and their mothers. These differences may lead to male fetuses exhibiting different endocrine metabolism characteristics compared to female fetuses 49 , 51 . Compared with living in rural areas, living in urban areas significantly reduced the risk of LBW. This may be related to the following characteristics of rural areas: first, early marriage and childbearing are more common, and residents generally have lower educational levels and insufficient awareness of prenatal care. Second, rural areas tend to have lower economic levels, with a lack of formal prenatal checkups and comprehensive pregnancy and delivery care services 28 , 52 . Therefore, in rural areas, it is essential to enhance the dissemination of prenatal healthcare knowledge, improve grassroot-level medical services, and increase residents’ cultural literacy. Regions with higher per capita GDP and a greater number of health workers were protective factors against LBW in Hainan. Erasun et al. reported that per capita GDP was negatively correlated with the LBW rate. Additionally, health-system factors, including health coverage and investment in the public health system, are directly associated with lower LBW rates. This study had several strengths. First, the study spanned a substantial period of 11 years (2010–2021), allowing for a comprehensive and systematic examination of long-term trends and short-term fluctuations in the incidence rates of LBW, VLBW, and ELBW in Hainan. This extensive timeframe provides a robust foundation for understanding dynamic changes in these indicators. Second, this study transcends the limitations of unidimensional analysis by integrating temporal trend analysis with geographical distribution research. Through this spatiotemporal coupling approach, the study not only reveals regional disparities in LBW and other indicators across Hainan, but also further explores their clustering and diffusion characteristics within different geographical units. This study provides a scientific basis for accurately identifying high-risk areas and optimizing the allocation of regional public health resources. In addition to conducting a thorough analysis of LBW, this study identified key factors influencing its occurrence, thereby offering targeted empirical support for the formulation and optimization of public health policies. The research outcomes provide a strong theoretical basis and decision-making reference for public health practices in Hainan, effectively contributing to the improvement of neonatal health and the enhancement of public health resource allocation efficiency in the region. However, as a retrospective cohort study, this research has the limitation of incomplete collection of potential risk factors for low birth weight. It can only identify relevant factors at a macroscopic level and has not delved into the underlying biological mechanisms and social behavioral pathways. Future studies could consider employing prospective cohort studies or multi-center collaborations to systematically and comprehensively collect data on risk factors. On this basis, integrating multidisciplinary approaches can further elucidate the micro-level mechanisms of action of risk factors and their social impact pathways, thereby providing a more robust foundation for refining theoretical frameworks and formulating evidence-based intervention strategies. In summary, the incidence of LBW in Hainan showed an increasing trend after 2015 during the period from 2010 to 2017, whereas the incidence rates of VLBW and ELBW were increasing throughout the observation period. This situation should attract significant attention from the government and relevant departments. To address this issue, it is essential to enhance preventive measures for LBW, with a particular focus on high-risk groups, including young and older mothers, primiparous women, women with multiple pregnancies, parents belonging to ethnic minorities, and those delivering in tertiary medical institutions. Additionally, regular prenatal check-ups and health education should be promoted to facilitate the timely identification of potential risk factors. Declarations Author contributions Ping-Hao Chen, Wei-Jia Wu and Bo-Wei Zhang drafted the manuscript. Xue-Lu Lei, Zhen-Ning Huang, Chun-Hui Zhang, and Chen Wang analyzed the data. Ping Wang, Qiu-Jing Chen, Xiao-Tu Yang, and Chui-Can Huang collected data. Qing Luo and Fan Lichun designed the study and revised the manuscript. All the authors reviewed the manuscript. Acknowledgments We sincerely appreciate the strong support of the Hainan Province Children’s Health and Disease Clinical Research Center for this project, and we extend our heartfelt thanks to all staff members who participated in this study. Funding This work was supported by the Major Science and Technology Project of Hainan Province (No.ZDKJ2019010), Key Research and Development Project of Hainan Province (No. ZDYF2020210), the Excellent Talent Team of Hainan Province (No. QRCBT202121), the Hainan Provincial Science and Technology Program for Clinical Medical Research Center (No. LCYX202405), International Science & Technology Cooperation Program of Hainan Province (No.GHYF2025042), and the Hainan Provincial Science and Technology Program for Clinical Medical Research Center(No.LCYX202506). Data availability statement All data generated or analysed during this study are included in this published article. For further inquiries, please contact the corresponding author directly. Ethical approval This study has been approved by the Medical Ethics Committee of Hainan Women and Children's Medical Center (Ethics Approval Number: HNWCMC Ethics Review Number [21]/2025). Conflict of interest No financial or non-financial benefits have been received or will be received from any party related directly or indirectly to the subject of this article. The authors have no conflict of interest to declare. References Okwaraji YB, Krasevec J, Bradley E, Conkle J, Stevens GA, Gatica-Dominguez G, et al. National, regional, and global estimates of low birthweight in 2020, with trends from 2000: a systematic analysis. Lancet. 2024;403:1071–80. Chen Y, Li GH, Zou LY, Ruan Y, Wang X, Zhang WY. [Factors influencing low birth weight in China]. Zhonghua Wei Chan Yi Xue Za Zhi 2015;18:755 – 60.[in chinese]. Zheng S, Cao Y, Strasser S, Wei H. Prevalence and risk factors of low birth weight in the United States: An analysis of 2016–2021 data. Am J Hum Biol. 2024;36:e24016. 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[Study on the relationship between frequencies of prenatal care and neonatal low birth weight in women of childbearing age from rural areas of Shaanxi province]. Zhonghua Liu Xing Bing Xue Za Zhi. 2017;38:478–81. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 24 Nov, 2025 Reviewers agreed at journal 24 Nov, 2025 Reviewers invited by journal 12 Nov, 2025 Editor invited by journal 19 Oct, 2025 Editor assigned by journal 05 Aug, 2025 Submission checks completed at journal 05 Aug, 2025 First submitted to journal 05 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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07:12:09","extension":"html","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":175985,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7302578/v1/6f4f69a2996a03bbeca7b1ea.html"},{"id":96711529,"identity":"cf2b8967-f2f7-4afd-823b-d661015e8d94","added_by":"auto","created_at":"2025-11-25 10:12:10","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":842754,"visible":true,"origin":"","legend":"\u003cp\u003eChanging trends of the incidence rates of low birth weight, very low birth weight and extremely low birth weight in Hainan Island from 2010 to 2021\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7302578/v1/7121578b6663385fd07b4ec1.jpg"},{"id":96693404,"identity":"c3ef5c07-844a-45bd-9a9d-e8bacfa0505e","added_by":"auto","created_at":"2025-11-25 07:12:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":457545,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the incidence rates of LBW, VLBW, and ELBW in various cities and counties of Hainan Island\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7302578/v1/1f80150d15367746b328bb0b.png"},{"id":96712909,"identity":"621944e6-2ea6-436a-aad3-35623be6831f","added_by":"auto","created_at":"2025-11-25 10:17:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2403266,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7302578/v1/f834241d-0d03-4a0e-a785-1ccd1cbf05ff.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Long-term Trends and Influencing Factors of Low Birth Weight in Hainan Island, China's Largest Free Trade Zone: A Retrospective Study from 2010 to 2021","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eLow birth weight (LBW) is defined as birth weight of \u0026lt;\u0026thinsp;2,500 grams. Common etiologies include preterm birth, intrauterine fetal growth restriction, or a combination of both\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. A meta-analysis published in The Lancet reported a global LBW prevalence of 14.7% in 2020. South Asia had the highest prevalence at 24.4%, followed by sub-Saharan Africa at 13.9%. In contrast, North America, Australia, New Zealand, Central Asia, and Europe have lower prevalence rates, averaging 7.2%\u003csup\u003e1\u003c/sup\u003e. A national survey in China reported an LBW incidence of 7.21%\u003csup\u003e2\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eLow birth weight reflects a multitude of public health issues and is closely associated with adverse perinatal outcomes, neonatal diseases, neonatal mortality, and child health problems\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. It LBW is a significant predictor of neonatal and infant mortality and is associated with a higher risk of developing several chronic diseases in adulthood such as hypertension, type 2 diabetes, and coronary heart disease\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Additionally, LBW can affect neonatal growth and development, with adults born with LBW often experiencing a lower average height than their peers. Failure to achieve catch-up growth can adversely affect neurological and psychobehavioral development\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Moreover, LBW is closely associated with long-term social costs, as LBW infants often require specialized medical care, early intervention, and educational support, all of which place a significant burden on healthcare systems and social services\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. The ripple effects of LBW reflect in increased health-care expenditures and may also manifest through potential reductions in human capital and productivity\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Consequently, understanding the incidence of LBW and its associated risk factors is crucial to protect infant health, improve public health standards, and foster social welfare and economic prosperity. It also presents a critical opportunity to implement population-wide preventive health strategies\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eHainan Island, located at China\u0026rsquo;s southernmost point and the nation\u0026rsquo;s largest free trade port, experienced profound socioeconomic changes following the introduction of the Hainan Free Trade Port policies. These transformations have led to significant talent migration, the optimization of industrial structures, sustained economic growth, and notable societal development. Against this backdrop, our research team, supported by a major science and technology initiative on the island, conducted a comprehensive study on the growth and development of children aged 0\u0026ndash;18 years. This study established, for the first time, the standardized growth curves for this population. The comparison of the physical development indicators of children on Hainan Island with those from 35 years ago and against both Chinese and World Health Organization (WHO) standards revealed substantial improvements in the physical development of children in Hainan Island over the past three decades. However, these indicators still fall short of both national and international benchmarks. Longitudinal and cross-sectional analyses highlight persistent disparities; despite significant progress relative to historical data, the physical development on Hainan Island remains below the Chinese and WHO-based standards\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Preliminary studies have suggested that children on Hainan Island exhibit smaller statures than their domestic and international counterparts, raising concerns about whether they also experience higher LBW rates. Despite this, there is a lack of systematic research on the incidence and trends of LBW on Hainan Island.\u003c/p\u003e\u003cp\u003eTherefore, this study aims to construct a retrospective birth cohort from 2010 to 2021 to analyze the incidence and temporal trends of LBW on Hainan Island and to identify the risk factors associated with LBW. The findings provide a scientific basis for the prevention and management of LBW on Hainan Island, fill the gap in epidemiological data on LBW in China's tropical and subtropical regions, and offer strategic recommendations for reducing the incidence of LBW and improving maternal and child health in the Hainan Free Trade Port, thereby supporting the successful implementation of China's \"Universal Three-Child\" policy.\u003c/p\u003e"},{"header":"2 Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Study design\u003c/h2\u003e\u003cp\u003eThis observational study utilized data from the Hainan Province Birth Certificate System (HPBCS), which includes birth information for infants and children born alive in the province between January 1, 2010, and December 31, 2021. The inclusion criteria for this study were as follows: (1) children born between January 1, 2010, and December 31, 2021, and (2) neonates who obtained their birth medical certificate for the first time. The exclusion criteria were as follows: (1) neonates with unclear sex information or birth weight, and (2) neonates of foreign nationality.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Ethics statement\u003c/h2\u003e\u003cp\u003eThe study was conducted based on routinely collected health data from the Hainan Province Birth Certificate System without direct participation from the subjects. All data were anonymized to ensure that no personally identifiable information was included in the analysis. Because the data used in this study were encrypted and cannot be traced back to the individuals, informed consent was not required. The exemption from informed consent was approved by the Medical Ethics Committee of Hainan Women and Children\u0026rsquo;s Medical Center (Ethics Approval Number: HNWCMC Ethics Review No. [21] of 2025).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Data collection and quality control\u003c/h2\u003e\u003cp\u003eWe collected relevant data on the neonates and their parents from the HPBCS database. Neonatal data included sex, residential location, gestational age, and birth weight. The parental data included parental age, ethnicity, multiple pregnancies, parity, and delivery at tertiary hospitals. Additionally, this study gathered data on the per capita gross domestic product (GDP) and number of healthcare workers in various counties and cities of Hainan from the 2010 to 2021 editions of the Hainan Statistical Yearbook.\u003c/p\u003e\u003cp\u003eEstablished by the Hainan Provincial Health and Family Planning Commission, the HPBCS is managed by the Hainan Women and Children Medical Center, which permits the use of data from the system for medical research purposes. Birth information in the system is sourced from records registered by maternity institutions across the province. Quality control of birth data involves individual case verification during the entry of delivery information, validation when issuing birth medical certificates, and a three-tier quality control system for delivery registration information in the maternal and child health annual report. Each quality control level is overseen by designated personnel responsible for data collection, organization, review, and supervision.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Definitions\u003c/h2\u003e\u003cp\u003eThe data of newborns included sex (male or female), residential location (urban or rural), gestational age (preterm, full term, or postterm), and birth weight. Additionally, parental information included age, ethnicity (Han or ethnic minority), multiple pregnancies, parity, and the level of the medical institution where the delivery occurred (whether it was a tertiary hospital).\u003c/p\u003e\u003cp\u003eThe classification of the residence, whether rural or urban, was determined based on the family\u0026rsquo;s address and categorized using the urban/rural code provided by the National Bureau of Statistics of China. According to the WHO guidelines, preterm births were defined as those occurring before 37 weeks of gestation; full-term births, 37\u0026ndash;42 weeks; and, post-term births, after 42 weeks\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Multiple pregnancies were defined as those involving\u0026thinsp;\u0026ge;\u0026thinsp;2 fetuses in a single pregnancy. The National Health and Wellness Commission of the People's Republic of China classified hospitals as tertiary facilities based on their assessment criteria. The per capita GDP and number of healthcare personnel in various cities and counties in Hainan Province from 2010 to 2021 were divided into three levels based on the third percentile (low, middle, and high). Health personnel included medical, administrative, technical logistics, and other technical personnel.\u003c/p\u003e\u003cp\u003eIn line with the WHO standards\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, newborns with a birth weight of \u0026lt;\u0026thinsp;2500 g were classified as LBW. Based on birth weight, newborns were further categorized into LBW (birth weight less than 2500 g), very low birth weight (VLBW, \u0026lt;\u0026thinsp;1500 g), and extremely low birth weight (ELBW, \u0026lt;\u0026thinsp;1000 g) groups. The LBW incidence rate was defined as the proportion of LBW newborns among all live births in a given year, calculated as follows: LBW incidence rate = (number of LBW newborns / number of live births) \u0026times; 100%.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Statistical analysis\u003c/h2\u003e\u003cp\u003eThe incidence rate distribution maps of LBW, VLBW, and ELBW for each prefecture-level city and county on Hainan Island were created using ArcGIS software (version 10.8.1), and the spatial autocorrelations of LBW, VLBW, and ELBW were calculated for each prefecture-level city and county in Hainan Island. Joinpoint regression analysis was conducted using Joinpoint 4.9.0.1 software, with the incidence of LBW, VLBW, and ELBW as the dependent variables and year as the independent variable. This analysis calculated the annual percentage change (APC) and the average annual percentage change (AAPC), with statistical significance assessed based on 95% confidence intervals (CI)\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eCount data are presented as frequencies and percentages, and group comparisons were performed using the chi-square test. Univariate and multivariate unconditional binary logistic regression analyses were conducted to identify factors associated with LBW. First, crude odds ratios (OR) and 95% CI were calculated for each factor. Then, multivariate logistic regression was applied to estimate adjusted OR and their 95% CI. Analyses were performed using the SAS software (version 9.4; SAS Institute Inc., Cary, NC, USA). A \u003cem\u003eP\u003c/em\u003e-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant in a two-sided test.\u003c/p\u003e\u003c/div\u003e"},{"header":"3 Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Baseline characteristics\u003c/h2\u003e\u003cp\u003eA total of 1538,023 newborns were included, of whom 838,775 (54.54%) were male neonates, and 737,686 (51.91%) were born in urban areas. Among the parents of these newborns, the ages of the parents was predominantly 25\u0026ndash;34 years old, with 13,447,704 (87.43%) mothers aged 25\u0026ndash;34 years and 13,447,704 (87.43%) fathers aged 25\u0026ndash;34 years. In addition, parents were mostly of the Han nationality, with 1245,425 (80.98%) mothers and 1245,425 (80.98%) fathers of the Han nationality.\u003c/p\u003e\u003cp\u003eThe incidence of LBW infants on Hainan Island varied significantly across a number of population characteristics and environmental factors such as sex, residential location, parents\u0026lsquo; ethnic background, parents\u0026rsquo; age, gestational week of delivery, number of maternal deliveries, level of medical institution, level of per capita GDP, and number of health care workers (all \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDemographic characteristics and related factors of live births and their parents in Hainan, 2010\u0026ndash;2021\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariables\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-LBW\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLBW\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1538023 (100)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1446350 (94.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e91673 (5.96)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfant gender\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2073.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e699248 (45.46)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e650913 (93.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e48335 (6.91)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e838775 (54.54)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e795437 (94.83)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e43338 (5.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMultiple pregnancy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e95233.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1502871 (97.71)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1426834 (94.94)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e76037 (5.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e35152 (2.29)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e19516 (55.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15636 (44.48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaternal age (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1414.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e93740 (6.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e86170 (91.92)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e7570 (8.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e25\u0026ndash;34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1288991 (83.81)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1216122 (94.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e72869 (5.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e155292 (10.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e144058 (92.77)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e11234 (7.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epaternal age (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1049.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e83424 (5.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e76780 (92.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e6644 (7.96)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e25\u0026ndash;34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1344704 (87.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1267642 (94.27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e77062 (5.73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e109895 (7.15)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e101928 (92.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e7967 (7.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMother Ethnicity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1045.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ethe Han nationality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1245425 (80.98)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1174918 (94.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e70507 (5.66)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eethnic minority\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e292598 (19.02)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e271432 (92.77)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e21166 (7.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFather's ethnicity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1290.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ethe Han nationality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1293179 (84.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1219958 (94.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e73221 (5.66)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eethnic minority\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e244844 (15.92)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e226392 (92.46)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e18452 (7.54)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eResidential location\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e144.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUrban\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e737686 (51.91)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e694353 (94.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e43333 (5.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRural\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e683312 (48.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e639871 (93.64)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e43441 (6.36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTertiary hospital\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5654.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1287203 (83.69)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1218637 (94.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e68566 (5.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e250820 (16.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e227713 (90.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e23107 (9.21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGestational age\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e346662.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreterm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e86913 (5.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e41821 (48.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e45092 (51.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTerm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1426901 (92.78)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1380740 (96.76)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e46161 (3.24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOver-term\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e24209 (1.57)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e23789 (98.27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e420 (1.73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2966.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eprimiparity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e781416 (50.81)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e726845 (93.02)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e54571 (6.98)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emultiparity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e756607 (49.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e719505 (95.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e37102 (4.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGDP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e431.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e511057 (33.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e483255 (94.56)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e27802 (5.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMiddle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e511391 (33.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e480526 (93.96)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e30865 (6.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHigh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e515575 (33.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e482569 (93.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e33006 (6.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHealth personnel\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1323.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e509178 (33.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e481245 (94.51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e27933 (5.49)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMiddle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e516028 (33.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e487889 (94.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e28139 (5.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHigh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e512817 (33.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e477216 (93.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35601 (6.94)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eIn particular, the incidence of LBW was higher among girls than boys (6.91% vs. 5.17%). The prevalence of LBW was higher among children in rural areas than in urban areas (6.36% vs. 5.87%). The incidence of LBW babies was higher among newborns whose parents\u0026rsquo; ethnic background was ethnic minority than among those whose parents\u0026rsquo; ethnic background was the Han nationality (mother's ethnic background: 7.23% vs. 5.66%; father's ethnic background: 7.54% vs. 5.66%). The incidence of LBW was higher in newborns with parents aged\u0026thinsp;\u0026lt;\u0026thinsp;20 years than that in those with parents aged 25\u0026ndash;34 years and \u0026gt;\u0026thinsp;35 years (mother's age: 8.08% vs. 5.65% vs. 7.23% ; father's age: 7.96% vs. 5.73% vs. 7.25%).\u003c/p\u003e\u003cp\u003eThe incidence of LBW in multiple pregnancies was significantly higher than that in singleton pregnancies (44.48% vs. 5.06%). The incidence of LBW babies was significantly higher in preterm babies than those in term and expired neonates (51.88%, 3.23% vs. 1.73%). The incidence of LBW babies was higher among primiparous women than that in multiparous women (6.98% vs. 4.90%).\u003c/p\u003e\u003cp\u003eIn terms of the level of medical institution, the incidence of LBW babies was higher for newborns delivered at tertiary hospitals than in non-tertiary hospitals (9.21% vs. 5.33%). In terms of economic level, the incidence of LBW babies was higher in areas with high GDP per capita than in areas with low and medium GDP per capita (6.40% vs. 6.04% vs. 5.44%). In terms of health care resources, the incidence of LBW was higher in areas with a higher number of health care workers than in areas with a low and medium numbers of health care workers (6.94% vs. 5.45% vs. 5.49%).\u003c/p\u003e\u003cp\u003e\u003cb\u003e3.2 Incidence rate and changes in low birth weight infants in Hainan Island from 2010 to 2021\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAn analysis of LBW incidence from January 1, 2010, to December 31, 2021, in Hainan Province revealed an overall LBW incidence of 5.96%, with VLBW at 0.29% and ELBW at 0.02%. Among the 18 prefecture-level cities and counties in Hainan (excluding Sansha City), Wuzhishan City had the highest incidence rate of LBW at 7.41%, whereas Haikou City had the highest incidence rates of VLBW at 0.55% and ELBW at 0.06% (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). Spatial autocorrelation analysis revealed that the occurrences of LBW, VLBW, and ELBW infants on Hainan Island did not exhibit spatial autocorrelation and that they were randomly distributed. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn 2010, the incidence rates of LBW, VLBW, and ELBW in Hainan Province were 5.96%, 0.19%, and 0.01%, respectively. By 2021, these rates had risen to 6.61%, 0.48%, and 0.07%, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Joinpoint regression analysis indicated no significant changes in the incidence of LBW between 2010 and 2015 (APC = -0.7209, 95% CI: -2.4331-1.0214, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.3582). However, from 2015 to 2021, a significant increase in LBW incidence was observed (APC\u0026thinsp;=\u0026thinsp;1.9190, 95% CI: 0.5875\u0026ndash;3.2682, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0112). Over the period from 2010 to 2021, the VLBW incidence in Hainan showed no distinct joinpoints but exhibited a consistent increase (APC\u0026thinsp;=\u0026thinsp;AAPC\u0026thinsp;=\u0026thinsp;8.2298, 95% CI: 7.0264\u0026ndash;9.4468, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). Similarly, the incidence of ELBW demonstrated a notable upward trend (APC\u0026thinsp;=\u0026thinsp;AAPC\u0026thinsp;=\u0026thinsp;20.7718, 95% CI: 15.1269\u0026ndash;26.6934, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAPC and AAPC of low birth weight incidence rate in Hainan, China, 2010\u0026ndash;2021.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eType\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eYear\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003eAnnual percentage change\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003eAverage annual percent change\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAPC (95%CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003et\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAAPC (95%CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003et\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eLBW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2010\u0026ndash;2015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.7209(-2.4331-1.0214)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-0.9834\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.3582\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.7105(-0.1768-1.6057)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e1.5680\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.1169\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2015\u0026ndash;2021\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.9190(0.5875\u0026ndash;3.2682)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.1479\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0112\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVLBW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2010\u0026ndash;2021\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.2298(7.0264\u0026ndash;9.4468)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15.7595\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8.2298(7.0264\u0026ndash;9.4468)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e15.7595\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eELBW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2010\u0026ndash;2021\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.7718(15.1269\u0026ndash;26.6934)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8.7851\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e20.7718(15.1269\u0026ndash;26.6934)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e8.7851\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"8\"\u003eAPC:Annual percentage change; AAPC:Average annual percent change.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Identification of significant risk factors\u003c/h2\u003e\u003cp\u003eMultivariate logistic regression analysis identified several risk factors for LBW in Hainan Island, including parents aged\u0026thinsp;\u0026lt;\u0026thinsp;20 or \u0026gt;\u0026thinsp;35 years (AOR\u0026thinsp;=\u0026thinsp;1.213,1.049; 95% CI:1.172\u0026ndash;1.255, 1.019\u0026ndash;1.081; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001, 0.0015), prematurity (AOR\u0026thinsp;=\u0026thinsp;27.726; 95% CI: 27.233\u0026ndash;28.228; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), multiple pregnancies (AOR\u0026thinsp;=\u0026thinsp;7.669; 95% CI: 7.441\u0026ndash;7.904; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), primiparity (AOR\u0026thinsp;=\u0026thinsp;1.435; 95% CI: 1.411\u0026ndash;1.459; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), parents belonging to an ethnic minority (AOR\u0026thinsp;=\u0026thinsp;1.128, 1.313; 95% CI: 1.101\u0026ndash;1.155, 1.280\u0026ndash;1.347; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001, \u0026lt; 0.0001), and delivery in a tertiary medical institution (AOR\u0026thinsp;=\u0026thinsp;1.246; 95% CI: 1.218\u0026ndash;1.275; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001).\u003c/p\u003e\u003cp\u003eIn contrast, prolonged pregnancy (AOR\u0026thinsp;=\u0026thinsp;0.522; 95% CI: 0.472\u0026ndash;0.577; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), male sex (AOR\u0026thinsp;=\u0026thinsp;0.628; 95% CI: 0.617\u0026ndash;0.638; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), urban residence (AOR\u0026thinsp;=\u0026thinsp;0.805; 95% CI: 0.792\u0026ndash;0.818; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), areas with higher GDP per capita (AOR\u0026thinsp;=\u0026thinsp;0.903; 95% CI: 0.880\u0026ndash;0.927; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), and areas with a higher number of health care workers (AOR\u0026thinsp;=\u0026thinsp;0.955; 95% CI: 0.930\u0026ndash;0.981; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) were protective factors against LBW. (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e.Multiple logistic regression analysis of risk factors for low birth weight in Hainan, China 2010\u0026ndash;2021.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eVariables\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eLBW\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c10\" namest=\"c7\"\u003e\u003cp\u003eLBW\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUOR\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eAOR\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfant gender\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.310\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.734\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.724\u0026ndash;0.744\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.466\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.628\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.617\u0026ndash;0.638\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMultiple pregnancy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.710\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15.034\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14.703\u0026ndash;15.373\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2.039\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e7.686\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e7.457\u0026ndash;7.922\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaternal age\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.383\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.466\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.430\u0026ndash;1.503\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.193\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.213\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.172\u0026ndash;1.255\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e25\u0026ndash;34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.264\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.301\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.275\u0026ndash;1.329\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.048\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.049\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.019\u0026ndash;1.081\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.0015\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epaternal age\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.353\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.423\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.387\u0026ndash;1.461\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.179\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.153\u0026ndash;1.239\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e25\u0026ndash;34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.251\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.286\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.255\u0026ndash;1.317\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.102\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.108\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.071\u0026ndash;1.146\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMother Ethnicity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ethe Han nationality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eethnic minority\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.262\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.279\u0026ndash;1.321\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.128\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.101\u0026ndash;1.155\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFather's ethnicity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ethe Han nationality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eethnic minority\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.306\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.358\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.336\u0026ndash;1.381\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.313\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.280\u0026ndash;1.347\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eResidential location\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUrban\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.084\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.919\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.907\u0026ndash;0.932\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.217\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.805\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.792\u0026ndash;0.818\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRural\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTertiary hospital\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.590\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.804\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.776\u0026ndash;1.832\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.246\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.218\u0026ndash;1.275\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGestational age\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreterm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.473\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32.242\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e31.723\u0026ndash;32.769\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.322\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e27.726\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e27.233\u0026ndash;28.228\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTerm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOver-term\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.638\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.529\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.480\u0026ndash;0.582\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.650\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.522\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.472\u0026ndash;0.577\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrimiparous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.375\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.455\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.436\u0026ndash;1.476\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.361\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.435\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.411\u0026ndash;1.459\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emultiparous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGDP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMiddle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.110\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.116\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.098\u0026ndash;1.135\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.036\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.036\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1.013\u0026ndash;1.060\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.0023\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHigh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.173\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.189\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.169\u0026ndash;1.209\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.102\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.903\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.880\u0026ndash;0.927\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHealth personnel\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1 (ref)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMiddle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.006\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.994\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.977\u0026ndash;1.011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.454\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.025\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.975\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.952\u0026ndash;0.998\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.0311\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHigh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.251\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.285\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.265\u0026ndash;1.306\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.046\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.955\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.930\u0026ndash;0.981\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.0008\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"10\"\u003eAll odds ratios were mutually adjusted for other variables in the table. UOR:Un-adjusted odds Ratio.AOR:Adjusted odds Ratio.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eThis study, the first to comprehensively analyze LBW, VLBW, and ELBW epidemiology in Hainan using 2010\u0026ndash;2021 data, reveals that pre-2015 LBW incidence was 5.96%, with lower rates for VLBW and ELBW. Post-2015 saw a significant LBW increase, while VLBW and ELBW continued their upward trends. Geospatial analysis shows Wuzhishan City had the highest LBW rate, and Haikou the highest VLBW and ELBW rates, with no spatial autocorrelation observed. Key risk factors for LBW included preterm birth, multiple pregnancies, primiparity, minority ethnicity, and delivery in tertiary institutions. Protective factors comprised post-term pregnancy, male sex, urban residence, higher regional GDP, and more healthcare workers. These findings offer crucial evidence for shaping maternal and child health policies in Hainan.\u003c/p\u003e\u003cp\u003eBetween 2010 and 2021, the overall LBW incidence in Hainan Island was 5.96%. These rate is lower than those reported in the United Kingdom (6.8%), Portugal (8.9%), Spain (7.5%), Greece (9.9%), the United States (8.3%), South Korea (6.6%), Japan (9.4%), and several African nations (10.0\u0026ndash;15.7%) as well as the national average in China (7.21%)\u003csup\u003e2,13\u003c/sup\u003e. Compared to other regions in mainland China, the LBW incidence in Hainan Island was higher than in Beijing (4.23%)\u003csup\u003e14\u003c/sup\u003e, Chongqing (1.7%)\u003csup\u003e15\u003c/sup\u003e, and Inner Mongolia Autonomous Region (2.7%)\u003csup\u003e16\u003c/sup\u003e, but lower than that in Guangxi Province (8.05%)\u003csup\u003e17\u003c/sup\u003e. The variation in LBW incidence across regions can be attributed to a combination of factors including socio-political policies, social welfare systems, healthcare service coverage, public health infrastructure, and demographic characteristics. Collectively, these factors influence maternal health and prenatal care quality, thereby affecting the incidence of LBW in newborns\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn Hainan Island, Wuzhishan City exhibited a relatively high incidence of LBW, whereas Haikou City was characterized by higher rates of VLBW and ELBW. The results showed that Wuzhishan City exhibited a relatively high incidence of LBW (7.41%), possibly due to its geographical location, economic development, and distribution of medical resources. Located in the central region of Hainan Island, Wuzhishan is at a high altitude and has a large ethnic minority population. Its mountainous terrain limits transportation and economic development and contributes to the relative scarcity of medical resources. In contrast, Haikou City had higher rates of VLBW (0.55%) and ELBW (0.06%). As the provincial capital with abundant high-quality medical resources, Haikou City is equipped to provide advanced diagnostic and treatment services to critically ill pregnant women, which may facilitate the survival of more VLBW and ELBW infants. The Hainan provincial government has recognized these challenges and is actively implementing measures to enhance maternal and child health.\u003c/p\u003e\u003cp\u003eJoinpoint regression analysis results indicated that from 2010 to 2015, the incidence of LBW in Hainan Island remained stable, with no significant upward or downward trends. However, from 2015 to 2021, an upward trend was observed, with the LBW rate reaching 6.61% by 2021. This increase may be attributed to factors such as changes in fertility policies, the widespread adoption of assisted reproductive technology, and environmental and climatic influences. Since the introduction of the \"one couple, two children if one is an only child\" policy in 2013, followed by the \"universal two-child\" policy in 2016 and the \"three-child policy\" in 2021, China's successive relaxation of fertility policies has likely encouraged more older parents to have children\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. However, advanced maternal age is associated with a higher risk of maternal comorbidities (e.g., gestational hypertension and diabetes) and obstetric complications (e.g., miscarriage, preterm birth, and fetal growth restriction), all of which are established risk factors for LBW\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Additionally, paternal age should not be overlooked because it can affect offspring birth outcomes by influencing sperm epigenetics characterized by increased methylation, DNA fragmentation, telomere elongation, mutations, and genomic instability\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Climate change, along with the continued reliance on fossil fuels, has led to higher levels of PM\u003csub\u003e2.5\u003c/sub\u003e and ozone in the atmosphere, which are linked to a higher risk of LBW\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. Additionally, with the expanding use of assisted reproductive technologies and their markedly enhanced success rates, epidemiological studies have demonstrated a corresponding increase in the incidence of LBW among assisted reproductive technology-conceived offspring\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eBetween 2010 and 2021, the incidence of ELBW and VLBW infants in Hainan Island showed an increasing trend (both \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, the Birth Certificate System in Hainan Province meticulously records data of surviving newborns, indirectly reflecting the increasing survival rates of ELBW and VLBW infants in the region. This trend may be attributed to advancements in clinical rescue techniques, improvements in prenatal and perinatal healthcare, and enactment and enforcement of national policies, all of which have contributed to a general reduction in the mortality rates of ELBW and VLBW infants\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThe multivariate logistic regression analysis revealed that preterm birth, multiple gestation, primiparity, parents aged\u0026thinsp;\u0026lt;\u0026thinsp;20 or \u0026gt;\u0026thinsp;35 years, ethnic minority background status of parents, and delivery at tertiary hospitals were significant risk factors for LBW in Hainan Island. Preterm birth exhibited the highest risk ratio among these factors, aligning with previous studies\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. This is primarily because birth weight is largely determined by the duration of pregnancy and fetal growth rate\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. The later stages of pregnancy, particularly between 28 and 36 weeks of gestation, are crucial for rapid fetal growth. Preterm birth reduces the time available for fetal development in utero, thereby significantly affecting birth weight. Thus, the early identification and proper management of gynecological, obstetric, or other systemic conditions that may lead to preterm birth are essential for maximizing fetal development and reducing the incidence of LBW.\u003c/p\u003e\u003cp\u003eMultiple pregnancies increased the risk of LBW, which is consistent with prior research\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. This higher risk can be attributed to the higher likelihood of pregnancy complications, such as hypertension, intrauterine growth restriction, and placental abruption, which are common in multiple pregnancies\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e.These conditions often lead to preterm birth, subsequently affecting birth weight. This phenomenon may also be attributed to the fact that the critical physiological resources essential for fetal development are competitively allocated between twin fetuses during multifetal pregnancies\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Although multiple pregnancies are not modifiable factors for reducing the LBW incidence, the identification and effective management of health conditions in women with multiple pregnancies play a significant role in mitigating the risk of LBW.\u003c/p\u003e\u003cp\u003eParity is an important predictor of LBW in neonates. Primiparous women have a higher risk of delivering LBW infants\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e,\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. The results of this study also support this notion, with primiparous women having a 1.435-fold higher risk of LBW than multiparous women. Hinkle et al\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. found that the relationship between birth weight and parity was nonlinear, with birth weight increasing incrementally with increasing parity and stabilizing between the fourth and seventh deliveries. This phenomenon may be related to physiological changes that promote fetal growth during pregnancy and are not fully reversed postpartum, thereby creating a more effective foundation for subsequent pregnancies\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e. In particular, compared with that in a non-pregnant uterus, the uteroplacental blood flow responsible for delivering oxygen and nutrients to the fetus is greater in subsequent pregnancies\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Additionally, structural factors may limit uterine capacity during the first pregnancy, whereas the size and protein content of the uterus increase correspondingly with increasing parity\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Firstborn infants may be exposed to a distinct maternal immune environment compared to that in subsequent pregnancies, which may result in relatively restricted growth\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. Although the incidence of LBW deliveries is higher among multiparous women than that among primiparous women, this may be more closely related to the high parity associated with a history of abortions\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Therefore, the findings suggest that, following the relaxation of fertility policies in China, the impact of increased parity on the incidence of LBW may be relatively minor.\u003c/p\u003e\u003cp\u003eCompared to parents aged 25\u0026ndash;34 years, those aged\u0026thinsp;\u0026lt;\u0026thinsp;20 years or \u0026gt;\u0026thinsp;35 years were at an increased risk of LBW. Consistent with previous research findings\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e, the risk of LBW infants among young pregnant women is significantly higher, which may be closely related to the following factors: inadequately developed and matured physiological functions of the mother, relatively low cultural and educational levels; poor economic status, and lack of comprehensiveness in prenatal care measures\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. In addition, the biological impact of paternal age on birth outcomes stems from the fact that gene expression of the father's genes in the placenta is higher, and compared to mature and older men, there is a greater likelihood of mutations in these genes in younger and less mature men\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. Advanced maternal age is associated with a higher incidence of pregnancy comorbidities (such as hypertension and diabetes) and a significant increase in the occurrence of pregnancy complications (such as miscarriage, preterm birth, placenta previa, stillbirth, and fetal growth restriction), which, in turn, leads to an increased risk of LBW\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. In fathers, advanced age can exert epigenetic effects on the sperm, which are characterized by increased sperm DNA methylation, DNA fragmentation, telomere shortening, increased mutations, and reduced overall genomic stability\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. These changes make advanced paternal age an important factor influencing offspring birth outcomes and may further increase the risk of LBW.\u003c/p\u003e\u003cp\u003eIn this study, an ethnic minority status was associated with a higher risk of LBW, consistent with previous research. This may be linked to the lower socioeconomic status in areas where ethnic minorities are concentrated in Hainan. Mothers from impoverished families are more likely to give birth to LBW infants compared to those from wealthier families, primarily because of inadequate access to good nutrition and prenatal care\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. Moreover, factors such as poverty, discrimination, and low education levels increase the risk of preterm birth or intrauterine growth restriction in minority populations, which in turn contribute to LBW\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. In ethnic minority-inhabited regions, it is crucial to increase economic support, improve nutritional and medical conditions, provide personalized healthcare services, eliminate discrimination, and safeguard fair rights and interests, all of which aim to reduce the risk of low birth weight occurrence.\u003c/p\u003e\u003cp\u003eThe study also revealed that delivery at a tertiary medical institution was an independent risk factor for LBW. Tertiary hospitals, the highest-level healthcare units, offer advanced medical facilities and diagnostic technologies, which make them the primary providers for high-risk pregnancies. Consequently, a higher proportion of pregnancy-related complications are managed in these institutions, leading to a higher incidence of LBW infants in these settings\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eConversely, post-term pregnancy, male sex of the neonate, urban residence, regions with higher per capita GDP, and areas with a greater number of health workers are protective factors against LBW in Hainan.\u003c/p\u003e\u003cp\u003ePostterm pregnancy reduced the risk of LBW, which may indirectly decrease the risk of LBW infants by increasing the risk of macrosomia\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e. This study showed that female sex of the infant is a risk factor for developing small for gestational age infants, which is consistent with relevant research results. This phenomenon may be related to biological differences in fetal sex, as there are differences in antigen or androgen levels between fetuses of different sexes and their mothers. These differences may lead to male fetuses exhibiting different endocrine metabolism characteristics compared to female fetuses\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e,\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eCompared with living in rural areas, living in urban areas significantly reduced the risk of LBW. This may be related to the following characteristics of rural areas: first, early marriage and childbearing are more common, and residents generally have lower educational levels and insufficient awareness of prenatal care. Second, rural areas tend to have lower economic levels, with a lack of formal prenatal checkups and comprehensive pregnancy and delivery care services\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. Therefore, in rural areas, it is essential to enhance the dissemination of prenatal healthcare knowledge, improve grassroot-level medical services, and increase residents\u0026rsquo; cultural literacy.\u003c/p\u003e\u003cp\u003eRegions with higher per capita GDP and a greater number of health workers were protective factors against LBW in Hainan. Erasun et al. reported that per capita GDP was negatively correlated with the LBW rate. Additionally, health-system factors, including health coverage and investment in the public health system, are directly associated with lower LBW rates.\u003c/p\u003e\u003cp\u003eThis study had several strengths. First, the study spanned a substantial period of 11 years (2010\u0026ndash;2021), allowing for a comprehensive and systematic examination of long-term trends and short-term fluctuations in the incidence rates of LBW, VLBW, and ELBW in Hainan. This extensive timeframe provides a robust foundation for understanding dynamic changes in these indicators. Second, this study transcends the limitations of unidimensional analysis by integrating temporal trend analysis with geographical distribution research. Through this spatiotemporal coupling approach, the study not only reveals regional disparities in LBW and other indicators across Hainan, but also further explores their clustering and diffusion characteristics within different geographical units. This study provides a scientific basis for accurately identifying high-risk areas and optimizing the allocation of regional public health resources. In addition to conducting a thorough analysis of LBW, this study identified key factors influencing its occurrence, thereby offering targeted empirical support for the formulation and optimization of public health policies. The research outcomes provide a strong theoretical basis and decision-making reference for public health practices in Hainan, effectively contributing to the improvement of neonatal health and the enhancement of public health resource allocation efficiency in the region. However, as a retrospective cohort study, this research has the limitation of incomplete collection of potential risk factors for low birth weight. It can only identify relevant factors at a macroscopic level and has not delved into the underlying biological mechanisms and social behavioral pathways. Future studies could consider employing prospective cohort studies or multi-center collaborations to systematically and comprehensively collect data on risk factors. On this basis, integrating multidisciplinary approaches can further elucidate the micro-level mechanisms of action of risk factors and their social impact pathways, thereby providing a more robust foundation for refining theoretical frameworks and formulating evidence-based intervention strategies.\u003c/p\u003e\u003cp\u003eIn summary, the incidence of LBW in Hainan showed an increasing trend after 2015 during the period from 2010 to 2017, whereas the incidence rates of VLBW and ELBW were increasing throughout the observation period. This situation should attract significant attention from the government and relevant departments. To address this issue, it is essential to enhance preventive measures for LBW, with a particular focus on high-risk groups, including young and older mothers, primiparous women, women with multiple pregnancies, parents belonging to ethnic minorities, and those delivering in tertiary medical institutions. Additionally, regular prenatal check-ups and health education should be promoted to facilitate the timely identification of potential risk factors.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePing-Hao Chen, Wei-Jia Wu and Bo-Wei Zhang drafted the manuscript. Xue-Lu Lei, Zhen-Ning Huang, Chun-Hui Zhang, and Chen Wang analyzed the data. Ping Wang, Qiu-Jing Chen, Xiao-Tu Yang, and Chui-Can Huang collected data. Qing Luo and Fan Lichun designed the study and revised the manuscript. All the authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe sincerely appreciate the strong support of the Hainan Province Children\u0026rsquo;s Health and Disease Clinical Research Center for this project, and we extend our heartfelt thanks to all staff members who participated in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Major Science and Technology Project of Hainan Province (No.ZDKJ2019010), Key Research and Development Project of Hainan Province (No. ZDYF2020210), the Excellent Talent Team of Hainan Province (No. QRCBT202121), the Hainan Provincial Science and Technology Program for Clinical Medical Research Center (No. LCYX202405), International Science \u0026amp; Technology Cooperation Program of Hainan Province (No.GHYF2025042), and the Hainan Provincial Science and Technology Program for Clinical Medical Research Center(No.LCYX202506).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll\u0026nbsp;data\u0026nbsp;generated\u0026nbsp;or\u0026nbsp;analysed\u0026nbsp;during\u0026nbsp;this\u0026nbsp;study\u0026nbsp;are\u0026nbsp;included\u0026nbsp;in\u0026nbsp;this\u0026nbsp;published\u0026nbsp;article.\u0026nbsp;For\u0026nbsp;further\u0026nbsp;inquiries,\u0026nbsp;please\u0026nbsp;contact\u0026nbsp;the\u0026nbsp;corresponding\u0026nbsp;author\u0026nbsp;directly.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study has been approved by the Medical Ethics Committee of Hainan Women and Children\u0026apos;s Medical Center (Ethics Approval Number: HNWCMC Ethics Review Number [21]/2025).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo financial or non-financial benefits have been received or will be received from any party related directly or indirectly to the subject of this article. The authors have no conflict of interest to declare.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eOkwaraji YB, Krasevec J, Bradley E, Conkle J, Stevens GA, Gatica-Dominguez G, et al. National, regional, and global estimates of low birthweight in 2020, with trends from 2000: a systematic analysis. Lancet. 2024;403:1071\u0026ndash;80.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen Y, Li GH, Zou LY, Ruan Y, Wang X, Zhang WY. [Factors influencing low birth weight in China]. Zhonghua Wei Chan Yi Xue Za Zhi 2015;18:755\u0026thinsp;\u0026ndash;\u0026thinsp;60.[in chinese].\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZheng S, Cao Y, Strasser S, Wei H. Prevalence and risk factors of low birth weight in the United States: An analysis of 2016\u0026ndash;2021 data. 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Gender differences in developmental programming of cardiovascular diseases. Clin Sci (Lond). 2016;130:337\u0026ndash;48.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi JM, Liu DM, Zhang XF, Qu PF, Yan H. [Study on the relationship between frequencies of prenatal care and neonatal low birth weight in women of childbearing age from rural areas of Shaanxi province]. Zhonghua Liu Xing Bing Xue Za Zhi. 2017;38:478\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Hainan Free Trade Port, Low Birth Weight, Retrospective Cohort Study, Joinpoint Regression","lastPublishedDoi":"10.21203/rs.3.rs-7302578/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7302578/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eLow birth weight (LBW) poses substantial health risks for neonates and can have enduring consequences, such as higher healthcare costs and adverse effects on human capital and productivity. However, comprehensive epidemiological data on LBW in Hainan Province, China's Largest Free Trade Port and a strategically vital tropical region, remain strikingly limited. This study aims to assess the incidence of LBW in Hainan Free Trade Port and identify contributing risk factors.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis population-based retrospective cohort study analyzed 1,538,023 live births in Hainan Province from 2010 to 2021. Data on neonatal and parental demographics, clinical factors, and socioeconomic indicators were systematically collected. LBW, VLBW, and ELBW were classified based on birth weight. Spatial analysis used ArcGIS to assess geographic distribution. Temporal trends were analyzed via joinpoint regression. Multivariate binary logistic regression identified risk factors for LBW.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe overall LBW incidence was 5.96%, with VLBW at 0.29% and ELBW at 0.02%. Joinpoint regression identified distinct temporal patterns; although the LBW rate remained stable from 2010\u0026ndash;2015 (APC: -0.7209; 95% CI: -2.4331\u0026ndash;1.0214; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.3582), it increased significantly from 2015\u0026ndash;2021(APC: 1.9190; 95% CI: 0.5875\u0026ndash;3.2682; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0112). In contrast, both VLBW and ELBW showed sustained upward trends throughout the study period (APC\u0026thinsp;=\u0026thinsp;AAPC: 8.2298, 20.7718; 95% CI: 7.0264\u0026ndash;9.4468, 15.1269\u0026ndash;26.6934; both \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). The geospatial analysis identified regional heterogeneity, with Wuzhishan exhibiting the highest LBW incidence (7.41%), and Haikou showing peak rates of VLBW (0.55%) and ELBW (0.06%). The occurrence of LBW, VLBW, and ELBW in Hainan Province was distributed in a follow-up manner. Multivariate binary logistic regression analysis demonstrated that parental age (\u0026lt;\u0026thinsp;20 or \u0026gt;\u0026thinsp;35 years), minority ethnicity, preterm birth, multiple pregnancies, and delivery to a tertiary hospital were significantly associated with a higher risk of LBW. Conversely, male sex, post-term gestation, urban residency, higher regional GDP per capita, and a higher density of healthcare workers demonstrated significant protective effects against LBW.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThere's a significant increase in LBW - related incidences in Hainan. Targeted prevention for high - risk groups is needed.\u003c/p\u003e","manuscriptTitle":"Long-term Trends and Influencing Factors of Low Birth Weight in Hainan Island, China's Largest Free Trade Zone: A Retrospective Study from 2010 to 2021","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-25 07:12:04","doi":"10.21203/rs.3.rs-7302578/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-11-24T11:39:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93898639745356062000712117993953126016","date":"2025-11-24T07:32:13+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-12T19:44:01+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-19T15:15:52+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-06T00:06:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-06T00:05:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2025-08-05T15:52:59+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c4922e49-9a88-4fc2-8de4-dd4dd0999344","owner":[],"postedDate":"November 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-11-25T07:12:04+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-25 07:12:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7302578","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7302578","identity":"rs-7302578","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}