Impact of endometrial thickness alteration in response to progesterone administration on neonatal outcomes in frozen embryo transfer cycles: analysis of 6331 singleton newborns

Impact of endometrial thickness alteration in response to progesterone administration on neonatal outcomes in frozen embryo transfer cycles: analysis of 6331 singleton newborns | 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 Impact of endometrial thickness alteration in response to progesterone administration on neonatal outcomes in frozen embryo transfer cycles: analysis of 6331 singleton newborns Jing Ye, Jie Zhang, Tong Du, Sha Yu, Yanwen Zhu, Hongyuan Gao, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5278874/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Background To assess the impact of progesterone-induced changes in endometrial thickness (EMT) on singleton infant outcomes during frozen-thawed embryo transfer (FET) cycles. Methods This retrospective observational study included a total of 6331 singleton live births resulting from frozen-thawed Day 3 embryo transfer. Endometrial thickness (EMT) was assessed using transvaginal ultrasound one day prior to progesterone administration and on the day of frozen embryo transfer (FET) to examine any variations in EMT. The study population comprised 6331 women, who were categorized into three groups based on changes in EMT: the EMT increase group, the EMT decrease group, and the EMT stable group. The primary outcomes investigated in this study were mean birthweight, low birthweight (LBW), and small-for-gestational age (SGA). A multivariable linear regression analysis was performed to explore the association between changes in EMT following progesterone administration and newborns' birthweight. Results Despite any fluctuations in EMT levels on the day of FET compared to one day prior to progesterone administration, there were no statistically significant differences observed in the absolute mean birthweight of singletons among the three groups (3355.30 ± 502.69 vs. 3351.30 ± 474.79 vs. 3344.26 ± 514.54, P = 0.753). In comparison to the stable EMT group, the decreased EMT group had incidences of LBW and SGA in term infants at 1.1% (adjusted odds ratio [aOR]: 1.645, 95% confidence interval [CI]: 0.818–3.307) and 2.7% (aOR: 1.141, 95% CI:0.783–1.662), respectively; however, there was no significant association between the increased EMT group and risks of LBW (aOR: 1.310, 95% CI:0.723–2.375) or SGA (aOR:0.912, 95% CI:0.660–1.261). The multiple linear regression analysis revealed that both gestational age and infant gender exerted significant influences on singleton birthweight, while any alteration in endometrial thickness subsequent to progesterone administration did not yield a statistically significant impact on singleton birthweight. Conclusions The extent of EMT may exhibit variability, either increasing, decreasing, or remaining stable on the day of frozen embryo transfer (FET) compared to one day prior to progesterone administration. However, it is important to note that changes in EMT following progesterone administration do not demonstrate an independent association with adverse perinatal outcomes in term infants during FET cycles. Birthweight frozen-thawed embryo transfer endometrial thickness change Neonatal outcomes Background Since the advent of the first child conceived through in vitro fertilization (IVF) in 1978, there has been a significant increase in the number of children born worldwide using assisted reproductive technology (ART), with delivery rates steadily rising each year. The health implications associated with these ART-conceived children have garnered widespread public concern. Generally, the majority of offspring resulting from IVF exhibit good overall health status. However, pregnancies resulting from IVF are associated with an elevated risk of adverse perinatal outcomes, including preterm birth (PTB), low birthweight (LBW), and small for gestational age (SGA)( 1 , 2 ). The etiology of these inferior outcomes in ART singletons is multifactorial. Pinborg A et al. discovered that subfertility constitutes a significant risk factor for adverse perinatal outcomes in ART singletons. Furthermore, they observed that even within the same mother, an ART singleton exhibits poorer outcomes compared to its non-ART sibling. Consequently, they postulated that factors associated with hormone stimulation and/or IVF techniques themselves may also contribute (e.g., embryo culture media and duration of culture, as well as embryo cryopreservation)( 2 ). Emerging evidence further suggests that various factors associated with IVF procedures, such as patient characteristics, ovarian stimulation protocols, insemination techniques, cryopreservation methods, and the embryo culture medium employed, may also contribute to these suboptimal outcomes( 3 – 8 ). The assessment of birthweight in the ART population has been a frequent practice. Birthweight serves as a crucial parameter for evaluating neonatal health, as it is closely linked to mortality risk within the first year, developmental challenges during childhood, and susceptibility to various diseases in adulthood( 9 ). LBW, in relation to the duration of pregnancy and gestational age, has been found to be associated with elevated rates of coronary heart disease as well as its related conditions including stroke, hypertension, and type 2 diabetes( 10 ). The measurement of endometrial thickness (EMT) through transvaginal ultrasound (TVU) has gained widespread acceptance as a prognostic indicator for endometrial receptivity; however, the findings remain subject to controversy ( 11 – 18 ). In the majority of previous studies, monitoring of endometrial thickness occurred during ovarian stimulation in fresh embryo transfer cycles or during the proliferation phase prior to progesterone administration in frozen-thawed embryo transfer cycles. A plethora of evidence has consistently demonstrated that a reduction in peak endometrial thickness is significantly associated with diminished chances of pregnancy in both fresh and frozen-thawed embryo transfer (FET) cycles( 11 , 19 – 22 ). Barker et. al conducted an evaluation on the correlation between endometrial thickness during the luteal phase (specifically on the day of embryo transfer) and pregnancy outcomes in the oocyte donation model( 18 ). The dynamic nature of endometrial physiology and the differentiation between the follicular and luteal phases in both natural menstrual cycles and IVF treatment are widely acknowledged( 23 – 25 ). The endometrial pattern undergoes characteristic changes, transitioning from pattern A (a triple-line pattern comprising a central hyper-echoic line surrounded by two hypoechoic layers) to pattern B (an intermediate isoechogenic pattern with similar reflectivity as the surrounding myometrium and a poorly defined central echogenic line), and finally to pattern C (a homogeneous, hyperechogenic endometrium). Numerous published studies have examined the correlation between endometrial patterns and outcomes of assisted reproductive techniques, yielding conflicting conclusions( 25 – 29 ). To date, limited research has been conducted to investigate the potential correlation between changes in endometrial thickness in response to progesterone and neonatal outcomes. This study aims to analyze the variation in endometrial thickness (from the day of embryo transfer to the day prior to progesterone administration) and explore its impact on neonatal outcomes within FET cycles. Methods Study design and patients This retrospective study was conducted at the Department of Assisted Reproduction, Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine (Shanghai, China), involving a cohort of 6331 women who underwent frozen embryo transfer (FET) cycles between January 2010 and December 2019 in our center. The inclusion criteria encompassed women aged ≤ 40 years with a body mass index (BMI) < 30 kg/m 2 who received FET cycles in our center and had embryo transfer on day 3. Exclusion criteria comprised women with uterine malformation, endometriosis, adenomyosis, as well as endometrial polyps or submucosal myomas identified through hysteroscopy that could potentially impact embryo implantation. This observational study obtained approval from the Ethics Committee (Institutional Review Board) of Shanghai Ninth People's Hospital without any intervention. This study adhered to the principles outlined in the Helsinki Declaration. Treatment protocol Treatment protocol Endometrial preparation for frozen embryo transfer (FET) involved both artificial cycles (estrogen-progesterone cycle, EP) and natural cycles (NCs). In the NC group, all patients underwent ultrasonic evaluation starting from day 10 of their menstrual cycle. The endometrial thickness (EMT) and mean diameter of the dominant follicle were assessed by the same physician. Once the diameter of the dominant follicle reached approximately 18mm and EMT reached 7mm, a blood sample was collected to measure progesterone, estradiol (E 2 ), and luteinizing hormone (LH) levels. If the E2 level exceeded 150 pg/mL while progesterone remained below 1 ng/mL, one of two procedures was conducted based on serum LH values: if LH was less than 20 mIU/mL, a bolus dose of 5,000 IU human chorionic gonadotropin (hCG) was administered on the same night; three days later, progesterone supplementation commenced. Finally, five days after hCG injection, cleavage-stage embryos were transferred. In cases where the serum LH concentration was ≥ 20 mIU/mL, hCG administration took place on the same afternoon followed by progesterone administration after a two-day interval. The transfer of cleavage-stage embryos occurred four days later. The evaluation of endometrial thickness (EMT) on the day of hCG administration was documented using transvaginal ultrasound imaging. For EP cycles, patients initiated sequential oral administration of micronized estradiol (8mg/day) on cycle day 3. EMT ultrasound measurement was conducted 12–14 days after the initiation of micronized estradiol. Progesterone supplementation commenced when EMT reached 7mm. Patients initiated oral administration of yellow Fematon tablets, twice daily at a dosage of two tablets, each containing 2 mg micronized estradiol and 10 mg dydrogesterone (Abbott Healthcare Products B.V.). Additionally, soft vaginal P capsules were administered twice daily at a dosage of 200 mg each (Laboratoires Besins International). EMT on the day prior to progesterone administration was also documented through transvaginal ultrasound. Embryos were warmed and transferred on day 3 following P supplementation, with a maximum limit of two embryos for transfer. Please refer to previous studies for comprehensive information regarding the endometrial preparation process for frozen embryo transfer (FET) and the measurement method of endometrial thickness (EMT)( 21 , 30 , 31 ). EMT assessment Based on variations in EMT measurements between the day of embryo transfer and the day prior to progesterone administration, the patients were categorized into three distinct groups: individuals exhibiting a decline in EMT levels (Group 1), those with stable EMT values (Group 2), and subjects displaying an increase in EMT levels (Group 3). All ultrasound measurements were conducted by a senior technician utilizing the GE Voluson E8 (GE Healthcare, Austria). EMT was determined as the maximum distance between the endometrial-myometrial interface in the mid-sagittal plane, following our previously established methodology( 21 , 30 , 31 ). In NCs, the assessment of endometrial thickness before progesterone administration commenced from the day of human chorionic gonadotropin (hCG) administration. Conversely, in EP cycles, this evaluation was conducted based on the final ultrasound prior to initiating progesterone administration. Additionally, for all patients, transvaginal ultrasound was performed on the morning of embryo transfer to ensure exclusion of any endometrial cavity fluid or other unfavorable conditions that could impede successful embryo transfer. Outcome measures and definitions Live birth was defined as the delivery of a viable neonate after 24 or more weeks of gestation. In frozen cycles, gestational age (GA) was calculated from the day of embryo transfer, which was designated as Day 17 due to cryopreservation on Day 3( 32 ). Preterm birth and very preterm birth were defined as delivery occurring prior to 37 and 32 completed gestational weeks, respectively. Small for gestational age (SGA) and very small for gestational age (VSGA) were defined as birthweight falling below the 10th and 3rd percentiles for the corresponding gestational age, respectively. Large for gestational age (LGA) was defined as birth weight exceeding the 90th percentile for the given gestational age, while very large for gestational age (VLGA) was defined as birthweight surpassing the 97th percentile. Low birthweight (LBW), very low birthweight (VLBW), high birthweight (HBW), and very high birth weight (VHBW) were classified as having a birthweight less than 2500g, less than 1500g, greater than 4000g, and greater than 4500g, respectively. In addition, the Z-score was utilized to compute birthweight adjusted for gestational age and neonatal gender using the following formula: Z-score= (x − µ)/σ, where x represents the weight of an infant, µ denotes the mean birthweight for infants of the same sex and gestational age in the reference group, and σ signifies the standard deviation of the reference group. Birthweight percentiles as well as Z-score calculation were based on Chinese singleton newborns from a reference population stratified by neonatal gender and gestational age( 33 ). Data regarding pregnancy and neonatal outcomes were extracted from electronic medical records. Statistical analysis The baseline characteristics and neonatal outcomes were compared using one-way analysis of variance for continuous data, while χ 2 or Fisher's exact tests were employed for categorical data, as deemed appropriate. Multivariable logistic regression analysis was conducted to identify any associations between changes in EMT and neonatal outcomes, while multiple linear regression was employed to investigate the independent impact of EMT change on birthweight. The following confounding factors were included in all multivariable analyses: maternal age and body mass index (BMI), paternal age, parity, duration of infertility, previous small-for-gestational-age (SGA) infants, number of embryos transferred, type of endometrial preparation, rank of frozen embryo transfer cycle, pregnancy complications such as gestational diabetes, hypertension, pre-eclampsia and placenta previa), newborn gender and gestational age at birth. The reference group for comparison was the stable EMT group. Statistical significance was defined as a p-value less than 0.05. All data were analyzed using the Statistical Package for the Social Sciences for Windows (SPSS version 25.0). Results In this observational study, the final dataset comprised 6331 women who met the inclusion criteria, with no loss to follow-up. The baseline demographic and cycle characteristics of all patients are presented in Table 1 based on EMT changes. Among all FET cycles, EMT decreased in 1746 patients and increased in 2835 patients on the day of embryo transfer. Comparison among the three groups did not reveal any significant differences for maternal age and BMI, paternal age, infertility cause, previous SGA babies, or FET cycle rank. However, parity, infertility duration, FET endometrial preparation, and number of embryos transferred differed significantly across EMT change categories. Neonatal outcomes stratified by changes in EMT status are also presented in Table I and Table II. There were no significant differences observed across the three groups in terms of newborn gender, distribution of gestational age, and occurrence of pregnancy-related complications. Similarly, the mean birthweight did not significantly differ among the three groups (3355.30 ± 502.69g vs. 3351.30 ± 474.79 vs. 3344.26 ± 514.54, P = 0.753). However, when considering the mean birthweight Z-scores categorized by EMT changes, a significant variation was noted between groups: Group 3 exhibited lower Z-scores (0.34 ± 1.07) compared to Group 1 (0.43 ± 1.04) and Group 2 (0.38 ± 1.04), with statistical significance at P < 0.05. Given the significance of gestational age at delivery as a crucial factor in determining newborn birthweight, we conducted a subgroup analysis by stratifying term (≥ 37 weeks) or preterm births (< 37 weeks). As depicted in Table III and Table IV, there was no statistically significant disparity observed in the mean birthweight of singletons among the three groups within the term (≥ 37 weeks) category. Compared to the stable group of EMT, the incidence rates of low birth weight (LBW) and small for gestational age (SGA) in term infants were 1.1% (adjusted odds ratio [aOR]: 1.645, 95% confidence interval [CI]: 0.818–3.307) and 2.7% (aOR: 1.141, 95% CI:0.783–1.662), respectively, in the decreased EMT group; however, there was no significant association between the increased EMT group and risks of LBW (aOR: 1.310, 95% CI:0.723–2.375) or SGA (aOR:0.912, 95% CI:0.660–1.261). In singletons delivered before < 37 weeks of gestation, Group 2 exhibited a statistically significant increase in mean birthweight compared to the other two groups (P = 0.025) for preterm infants. The incidence of LBW in preterm infants was highest in Group 3, however, there were no statistically significant differences observed among the three groups. It is noteworthy that Group 3 exhibited the highest occurrence of SGA preterm infants (aOR: 0.893, 95% CI: 0.090–8.898). Multiple linear regression analyses were conducted to examine the association between change in EMT and birthweight (Table V). Even after adjusting for various potential confounders, any alteration in EMT following progesterone administration did not have a statistically significant impact on newborns' birthweight. Furthermore, newborn gender (P < 0.001) and gestational age (P < 0.001) independently served as predictors for birthweight. Discussion In this retrospective analysis of 6331 live-born singletons, we present the initial evidence indicating that any alteration in EMT subsequent to progesterone administration does not exert a significant impact on the birthweight of newborns in frozen embryo transfer (FET) cycles. Neither a decrease nor an increase in EMT following progesterone administration is associated with elevated risks of PTB, LBW, SGA, or pregnancy-related complications in term infants. Upon adjusting for several potential confounders, both newborn gender (P < 0.001) and gestational age (P < 0.001) emerge as independent predictors of birthweight. In recent decades, considerable attention has been devoted to investigating the impact of EMT on the success rates of in vitro fertilization (IVF). Numerous studies have consistently demonstrated that a thin endometrial lining exerts an adverse influence on pregnancy outcomes( 11 , 22 , 34 , 35 ). Limited research has been dedicated to exploring the potential association between EMT and neonatal birthweight. In the initial investigation conducted by Chung et al., they examined various factors influencing adverse perinatal outcomes in pregnancies following IVF treatment, revealing a twofold increased risk of adverse perinatal outcome in individuals with EMT ≤ 10 mm compared to those with EMT > 12 mm(OR: 2.04; 95% CI: 1.09–3.83)( 36 ). Additionally, a significant protective effect on infant outcome was observed with an increase in endometrial thickness (OR: 0.89; 95% CI: 0.80–0.99). Specifically, for every millimeter decrease in endometrial thickness, there was a relative increase of 12% (1/0.89 = 1.12) in the risk of adverse perinatal outcomes( 36 ). However, no statistically significant difference in risk was observed when the analysis was limited to singletons (aOR: 1.66, 95% CI: 0.73–3.81)( 36 ). Another study revealed a positive correlation between EMT administered on the day of HCG trigger and neonatal birthweight, particularly in pregnancies complicated by obstetric factors( 37 ). The study also revealed that the increase in EMT no longer exhibited a significant association with birth weight in uncomplicated pregnancies( 37 ). Oron et al. demonstrated that an endometrial thickness of less than 7.5 mm was associated with a significantly increased risk for adverse obstetric outcomes (adjusted OR: 1.53; 95% CI: 1.03–2.42; P = 0.04). However, no significant difference in singleton live birth weight was observed( 16 ). Du et al. demonstrated that an EMT ≤ 7.5 mm was significantly associated with an elevated risk of LBW in 2,847 singletons resulting from fresh cycles ( 38 ). In a recent large-scale retrospective study involving 5,220 singleton newborns, it was observed that individuals with an endometrial thickness (EMT) of less than 8 mm had an adjusted odds ratio (aOR) of 1.57 (95% CI: 1.09–2.26) for low birth weight (LBW) in frozen embryo transfer (FET) cycles( 39 ). This finding is consistent with previous research conducted at our center ( 21 , 40 ). In most of the aforementioned studies, EMT was assessed during the proliferative phase prior to progesterone administration. However, it is important to note that endometrial development exhibits distinct physiological characteristics between the follicular and luteal phases. During the follicular phase, estrogen exerts its influence on the endometrium, promoting EMT and facilitating the linear growth of both endometrial glands and blood vessels( 23 ). Under the influence of progesterone, endometrial proliferation ceases within 2–3 days after ovulation( 23 ). Limited research has been conducted on the association between changes in EMT following progesterone administration and pregnancy as well as neonatal outcomes. Although a limited number of studies have assessed the changes in EMT during IVF stimulation( 24 , 25 , 27 , 41 – 43 ), their findings exhibit some conflicting conclusions. The prognostic utility of the EMT change, occurring between the third day of gonadotrophin stimulation and the day of hCG administration, in predicting pregnancy occurrence was reported to be insignificant by Zhao et al. Furthermore, their findings indicated that a combined assessment of EMT change and type failed to accurately predict clinical outcomes( 27 ). However, unfortunately, they neglected to investigate the correlation between changes in EMT following progesterone administration and the subsequent pregnancy and neonatal outcomes. Haas, J. et al. investigated the disparity in EMT between the late estrogen phase and the day of embryo transfer in 274 FET cycles, revealing a robust inverse correlation of high significance between pregnancy outcomes and changes in EMT( 41 ). However, there were several limitations in their study. Firstly, the EMT was assessed using different measurement methods: transabdominal ultrasound on the day of embryo transfer and vaginal ultrasound at the end of the estrogen phase. Secondly, only women undergoing the hormonal preparation protocol for the FET cycle were included. Lastly, they solely focused on evaluating ongoing pregnancy rates in the FET cycle and did not investigate any potential association between changes in EMT after progesterone administration and neonatal outcomes. Another study reported that an increased endometrial thickness following progesterone administration was associated with improved pregnancy outcomes( 42 ). However, the relationship between changes in EMT after progesterone administration and neonatal outcomes was not investigated. Our previous study demonstrated that irrespective of any changes in epithelial-mesenchymal transition (EMT) following progesterone administration, there was no significant impact on the clinical pregnancy rate (CPR) and live birth rate during the frozen embryo transfer (FET) cycle( 31 ). However, our previous investigation did not explore the association between EMT alterations after progesterone administration and neonatal outcomes. The present study, aimed at addressing the limitations of previous investigations, examined the precise impact of progesterone administration on EMT change and its association with neonatal outcomes in FET cycles. Our findings, based on a cohort of over 6000 singleton newborns conceived through FET cycles, unequivocally demonstrate that any alteration in EMT following progesterone administration does not exert a significant impact on the outcomes of term newborns in FET cycles. In this study, results from multiple linear regression analysis revealed that both newborn gender and gestational age independently predicted birthweight, which is consistent with existing literature( 21 , 44 , 45 ). Male neonates have been predicted to weigh 130g higher than female neonates. Each weekly increase in gestational age has been associated with a 172g rise in birthweight. To account for potential bias related to infant gender and gestational age, Z-scores were calculated and compared across the three groups, revealing consistently lower scores in Group 3. In our cohort, significant differences were observed among the three groups regarding baseline and cycle characteristics such as parity, infertility duration, FET endometrial preparation, and number of embryos transferred. However, based on the linear regression model analysis, these aforementioned confounders did not exert any influence on neonatal birthweight. Moreover, considering that pregnancy outcomes may impact birthweight, we conducted additional analyses both including and excluding this factor; nevertheless, consistent results were obtained. Several limitations were encountered in this study. Despite our meticulous review of the database using strict inclusion and exclusion criteria, the retrospective design constrained our findings. Additionally, to mitigate potential confounding effects of culture duration on FET outcomes, we focused exclusively on neonatal outcomes following day 3 embryo transfers( 46 ). A major strength of this study was the use of data from a single center, ensuring consistency in practice. Endometrial preparation protocols were highly consistent throughout the study period, and endometrial thickness measurements were conducted by the same doctor at our center. While there may have been some bias due to inter-observer variability or changes over time in measurement methods, we accounted for potential confounders that could have impacted our findings. Conclusions and Future Prospects The present large-scale single-center study provides valuable insights into the impact of progesterone administration-induced EMT changes on pregnancy outcomes in frozen embryo transfer (FET) cycles. Our findings indicate that any alterations in EMT following progesterone administration do not significantly affect the outcomes of term newborns in FET cycles. This novel discovery offers reassuring information for patients undergoing FET with EMT changes due to progesterone administration, regarding the health of their neonates. However, further prospective cohort studies with extended follow-up periods are warranted to validate these conclusions. Abbreviations EMT Endometrial Thickness FET Frozen-thawed Embryo Transfer IVF In vitro Fertilization ART Assisted Reproductive Technology SGA Small Gestational Age VSGA Very small for Gestational Age LGA Large for Gestational Age VLGA Very Large for Gestational Age LBW Low Birthweight VLBW Very Low Birthweight HBW High Birthweight VHBW Very High Birthweight PTB Preterm Birth Declarations Ethics approval and consent to participate This observational study obtained approval from the Ethics Committee (Institutional Review Board) of Shanghai Ninth People's Hospital without any intervention. This study adhered to the principles outlined in the Helsinki Declaration. Written informed consent was waived due to the retrospective study. Consent for publication Not applicable. Availability of data and materials The data that support the findings of this study are available from the corresponding author upon reasonable request. Competing interests The authors declare no competing interests. Funding This work was supported by the National Natural Science Foundation of China (grant numbers：82271732, 82001502) and Shanghai Science and Technology Innovation Fund (grant numbers: 22Y21900800). Author Contributions Statement KYP and CQJ provided overall supervision for the study, including overseeing procedures, conception, design, and completion. YS, ZYW, GHY and LYL were responsible for data collection. YJ, ZJ, and DT contributed to data analysis and manuscript drafting. YJ, ZJ, and DT made equal contributions to this article. All authors participated in the final interpretation of study data and revisions of the manuscript. Acknowledgments The authors express their gratitude to the nurses and laboratory staff of the Department of Assisted Reproduction for their invaluable contributions to this research. Additionally, the authors extend their appreciation to the infertile couples who willingly participated in this study. 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Decreased Endometrial Thickness Is Associated With Higher Risk of Neonatal Complications in Women With Polycystic Ovary Syndrome. Front Endocrinol. 2021;12:766601. Haas J, Smith R, Zilberberg E, Nayot D, Meriano J, Barzilay E et al. Endometrial compaction (decreased thickness) in response to progesterone results in optimal pregnancy outcome in frozen-thawed embryo transfers. Fertil Steril. 2019. Bu Z, Yang X, Song L, Kang B, Sun Y. The impact of endometrial thickness change after progesterone administration on pregnancy outcome in patients transferred with single frozen-thawed blastocyst. Reprod Biol Endocrinol. 2019;17(1):99. McWilliams GD, Frattarelli JL. Changes in measured endometrial thickness predict in vitro fertilization success. Fertil Steril. 2007;88(1):74–81. Lin S, Li M, Lian Y, Chen L, Liu P. No effect of embryo culture media on birthweight and length of newborns. Hum Reprod. 2013;28(7):1762–7. Nelissen EC, Van Montfoort AP, Coonen E, Derhaag JG, Geraedts JP, Smits LJ, et al. Further evidence that culture media affect perinatal outcome: findings after transfer of fresh and cryopreserved embryos. Hum Reprod. 2012;27(7):1966–76. Q JZYWHLXM. C, Y F, Effect of in vitro culture period on birth weight after vitrified-warmed transfer cycles: analysis of 4,201 singleton newborns. 2019;111(1):97–104. Tables Table I Baseline demographics, cycle characteristics and perinatal outcomes according to endometrial thickness change. Group1 (n=1746) Group2 (n=1750) Group3 (n=2835) P value Maternal age (y) 31.82±3.87 31.66±3.76 31.66±3.74 0.329 a Maternal BMI (kg/m 2 ) 21.58±2.94 21.53±2.85 21.54±3.01 0.854 a Paternal age (years) 33.92±5.03 33.79±4.85 33.71±4.93 0.361 a Infertility cause 0.142 b Female 977(56.0) 1006(57.5) 1540(54.3) Male 252(14.4) 263(15.0) 428(15.1) Mixed 367(21.0) 316(18.1) 608(21.4) Unexplained 150(8.6) 165(9.4) 259(9.1) Parity, n (%) 0.000 b First 874(50.1) 941(53.8) 1593(56.2) High order 872(49.9) 809(46.2) 1242(43.8) Infertility duration (y) 3.64±2.67 4.03±2.78 3.65±2.65 0.000 a FET cycle rank, n (%) 0.185 b First 1097(62.8) 1130(64.6) 1857(65.5) High order 649(37.2) 620(35.4) 978(34.5) FET endometrial preparation, n (%) 0.000 b Ovulatory cycle 1110(63.6) 1156(66.1) 1962(69.2) Artificial cycle 636(36.4) 594(33.9) 873(30.8) Number of embryos transferred, n (%) 0.029 b 1 150(8.6) 164(9.4) 205(7.2) 2 1596(91.4) 1586(90.6) 2630(92.8) Previous SGA newborns, n (%) 8(0.5) 3(0.2) 11(0.4) 0.314 c Newborn gender, n (%) 0.599 b Female 852(48.8) 866(49.5) 1360(48.0) Male 894(51.2) 884(50.5) 1475(52.0) Gestational age (weeks) , n (%) 0.367 b <37 129(7.4) 110(6.3) 184(6.5) ≥37 1617(92.6) 1640(93.7) 2651(93.5) Pregnancy-related complications 156(8.9) 173(9.9) 238(8.4) 0.229 b Birth weight (g) 3355.30±502.69 3351.30±474.79 3344.26±514.54 0.753 a Z-score 0.43±1.04 0.38±1.04 0.34±1.07 0.023 a SGA - small for gestational age. a One-way ANOVA. Values are mean±SD. b Pearson chi-square test. Values are number (percentage). c Fisher’s exact test. Values are number (percentage). Z-score: EMT increase group vs EMT decrease group (P=0.007). Table II Birth weights and birth weights categories of live born singletons Group1 (n=1746) Group2 (n=1750) Group3 (n=2835) P value Newborn gender, n (%) 0.599 b Female 852(48.8) 866(49.5) 1360(48.0) Male 894(51.2) 884(50.5) 1475(52.0) Mean birthweight (g) 3355.30±502.69 3351.30±474.79 3344.26±514.54 0.753 a Normal weight, 2500–4000 g, n (%) 1513(86.7) 1550(88.6) 2476(87.3) 0.070 b LBW ( 4000 g), n (%) 145(8.3) 110(6.3) 201(7.1) VHBW (> 4500 g), n (%) 15(0.9) 23(1.3) 29(1.0) VLBW (< 1500 g), n (%) 9(0.5) 4(0.2) 24(0.8) Very small for gestational age (<3rd percentile), n (%) 26(1.5) 33(1.9) 49(1.7) 0.133 b Small for gestational age (90th percentile) 242(13.9) 212(12.1) 334(11.8) Very large for gestational age (>97th percentile), n (%) 104(6.0) 86(4.9) 164(5.8) SGA - small for gestational age. LBW, low birth weight; VLBW, very low birth weight; HBW, high birth weight; VHBW, very high birth weight a One-way ANOVA. Values are mean±SD. b Pearson chi-square test. Values are number (percentage). Values are number (percentage). Z-score: EMT increase group vs EMT decrease group (P=0.007). Table III Birth weights and birth weights categories of live born singletons by gestational age. Group1 Group2 Group3 P value Gestational age≥37 weeks N(%) 1617 1640 2651 Newborn gender, n (%) 0.505 b Female 788(48.7) 817(49.8) 1272(48.0) Male 829(51.3) 823(50.2) 1379(52.0) Mean birthweight (g) 3423.65±424.872 3400.65±418.856 3410.05±423.527 0.294 a Normal weight, 2500–4000 g, n (%) 1439(89.0) 1485(90.5) 2390(90.2) 0.222 b LBW ( 4000 g), n (%) 145(9.0) 109(6.6) 200(7.5) VHBW (> 4500 g), n (%) 15(0.9) 22(1.3) 29(1.1) Very small for gestational age (<3rd percentile), n (%) 23(1.4) 28(1.7) 42(1.6) 0.807 b Small for gestational age (90th percentile), n (%) 230(14.2) 204(12.4) 323(12.2) 0.096 b Very large for gestational age (>97th percentile), n (%) 103(6.4) 80(4.9) 147(5.5) 0.178 b Gestational age < 37 weeks N 129 110 184 Newborn gender, n (%) 0.732 b Female 64(49.6) 49(44.5) 88(47.8) Male 65(50.4) 61(55.5) 96(52.2) Mean birthweight (g) 2498.57±605.965 2615.59±629.418 2396.39±732.408 0.025 a Normal weight, 2500–4000 g, n (%) 74(57.4) 65(59.1) 86(46.7) 0.067 b VLBW (< 1500 g), n (%) 9(7.0) 4(3.6) 24(13.0) LBW ( 4000 g), n (%) 0(0.0) 1(0.9) 1(0.5) VHBW (> 4500 g), n (%) 0(0.0) 1(0.9) 0(0.0) Very small for gestational age (<3rd percentile), n (%) 3(2.3) 5(4.5) 7(3.8) 0.632 c Small for gestational age (<10th percentile), n (%) 6(4.7) 11(10) 27(14.7) 0.017 c LBW, low birth weight; VLBW, very low birth weight; HBW, high birth weight; VHBW, very high birth weight a One-way ANOVA. Values are mean±SD. b Pearson chi-square test. Values are number (percentage). c Fisher’s exact test. Values are number (percentage). Table IV Crude and adjusted ORs for birth weights and birthweights categories in singleton births by gestational age. Group1 Group2 Group3 Gestational age≥37 weeks Very small for gestational age (<3rd percentile) Crude OR (95% CI) 1.204(0.690-2.099) Reference 1.079(0.666-1.748) AOR (95% CI) 1.368(0.732-2.554) Reference 1.064(0.619-1.827) Small for gestational age (90th percentile) Crude OR (95% CI) 0.808(0.677-0.963) Reference 0.972(0.826-1.143) AOR (95% CI) 0.822(0.676-1.000) Reference 0.950(0.793-1.138) Very large for gestational age (>97th percentile) Crude OR (95% CI) 0.754(0.558-1.018) Reference 0.766(0.550-1.067) AOR (95% CI) 0.874(0.661-1.155) Reference 0.848(0.624-1.154) Low birth weight(4000g) Crude OR (95% CI) 0.791(0.621-1.007) Reference 0.918(0.734-1.149) AOR (95% CI) 0.784(0.600-1.025) Reference 0.872(0.680-1.117) Very high birth weight (>4500g) Crude OR (95% CI) 1.452(0.751-2.809) Reference 1.229(0.704-2.147) AOR (95% CI) 1.679(0.805-3.502) Reference 1.200(0.653-2.204) Gestational age < 37 weeks Small for gestational age (<10th percentile) Crude OR (95% CI) 2.278(0.814-6.376) Reference 0.646(0.307-1.361) AOR (95% CI) 9.992(0.587-17.227) Reference 0.893(0.090-8.898) Low birth weight(<2500g) Crude OR (95% CI) 0.864(0.514-1.450) Reference 0.576(0.356-0.930) AOR (95% CI) 0.895(0.195-4.104) Reference 0.087(0.019-0.388) CI: confidence interval, OR: odds ratio, AOR: adjusted odds ratio Analyses were adjusted for maternal age and BMI, paternal age, infertility cause, parity, infertility duration, FET cycle rank, the type of endometrial preparation, number of embryos transferred, newborn sex, previous SGA newborns. Table V Results of multiple linear regression analysis on the birthweight of live-born singletons Model Non-standardized coefficients Standardized coefficients t P value B Std. error Beta Constant -3335.343 146.076 -22.833 0.000 FET cycle rank, High order (vs First) 6.485 10.922 0.006 0.594 0.553 Maternal age (y) 0.115 1.986 0.001 0.058 0.954 Paternal age (y) 0.179 1.484 0.002 0.121 0.904 Duration of infertility(y) -3.046 2.054 -0.016 -1.483 0.138 Parity, High order（vs First ) -8.629 10.794 -0.009 -0.799 0.424 Maternal BMI (kg/m 2 ) -0.655 1.767 -0.004 -0.370 0.711 FET endometrial preparation, Artificial cycle (vs Ovulatory cycle) -12.873 11.218 -0.012 -1.148 0.251 EMT: before progesterone administration (mm) 9.462 4.925 0.041 1.921 0.055 EMT: on the day of FET (mm) -10.407 4.545 -0.051 -2.290 0.022 EMT change Remain stable(reference) Increased -22.158 15.251 -0.022 -1.453 0.146 Decreased 1.561 15.245 0.001 0.102 0.918 No. of embryo transferred 5.084 18.880 0.003 0.269 0.788 Pregnancy-related complications, yes (vs no) -23.406 19.387 -0.013 -1.207 0.227 Infant gender boys (vs girls) 130.122 10.362 0.130 12.558 0.000 Gestational age (weeks) 172.641 3.275 0.560 52.707 0.000 Additional Declarations No competing interests reported. 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Medicine","correspondingAuthor":false,"prefix":"","firstName":"Qiuju","middleName":"","lastName":"Chen","suffix":""},{"id":368702739,"identity":"ae43ce87-021c-4d1b-b28c-c23d4627cd38","order_by":8,"name":"Yanping Kuang","email":"","orcid":"","institution":"Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Yanping","middleName":"","lastName":"Kuang","suffix":""}],"badges":[],"createdAt":"2024-10-17 01:38:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5278874/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5278874/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":67827087,"identity":"fa026698-e37d-4672-bbf0-a59bdebc81b0","added_by":"auto","created_at":"2024-10-30 06:38:11","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1038750,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5278874/v1/f28adc42-2f4a-4b28-b1b8-2dead5ea5b7d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of endometrial thickness alteration in response to progesterone administration on neonatal outcomes in frozen embryo transfer cycles: analysis of 6331 singleton newborns","fulltext":[{"header":"Background","content":"\u003cp\u003eSince the advent of the first child conceived through in vitro fertilization (IVF) in 1978, there has been a significant increase in the number of children born worldwide using assisted reproductive technology (ART), with delivery rates steadily rising each year. The health implications associated with these ART-conceived children have garnered widespread public concern. Generally, the majority of offspring resulting from IVF exhibit good overall health status. However, pregnancies resulting from IVF are associated with an elevated risk of adverse perinatal outcomes, including preterm birth (PTB), low birthweight (LBW), and small for gestational age (SGA)(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The etiology of these inferior outcomes in ART singletons is multifactorial. Pinborg A et al. discovered that subfertility constitutes a significant risk factor for adverse perinatal outcomes in ART singletons. Furthermore, they observed that even within the same mother, an ART singleton exhibits poorer outcomes compared to its non-ART sibling. Consequently, they postulated that factors associated with hormone stimulation and/or IVF techniques themselves may also contribute (e.g., embryo culture media and duration of culture, as well as embryo cryopreservation)(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Emerging evidence further suggests that various factors associated with IVF procedures, such as patient characteristics, ovarian stimulation protocols, insemination techniques, cryopreservation methods, and the embryo culture medium employed, may also contribute to these suboptimal outcomes(\u003cspan additionalcitationids=\"CR4 CR5 CR6 CR7\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe assessment of birthweight in the ART population has been a frequent practice. Birthweight serves as a crucial parameter for evaluating neonatal health, as it is closely linked to mortality risk within the first year, developmental challenges during childhood, and susceptibility to various diseases in adulthood(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). LBW, in relation to the duration of pregnancy and gestational age, has been found to be associated with elevated rates of coronary heart disease as well as its related conditions including stroke, hypertension, and type 2 diabetes(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe measurement of endometrial thickness (EMT) through transvaginal ultrasound (TVU) has gained widespread acceptance as a prognostic indicator for endometrial receptivity; however, the findings remain subject to controversy (\u003cspan additionalcitationids=\"CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). In the majority of previous studies, monitoring of endometrial thickness occurred during ovarian stimulation in fresh embryo transfer cycles or during the proliferation phase prior to progesterone administration in frozen-thawed embryo transfer cycles. A plethora of evidence has consistently demonstrated that a reduction in peak endometrial thickness is significantly associated with diminished chances of pregnancy in both fresh and frozen-thawed embryo transfer (FET) cycles(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Barker et. al conducted an evaluation on the correlation between endometrial thickness during the luteal phase (specifically on the day of embryo transfer) and pregnancy outcomes in the oocyte donation model(\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). The dynamic nature of endometrial physiology and the differentiation between the follicular and luteal phases in both natural menstrual cycles and IVF treatment are widely acknowledged(\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). The endometrial pattern undergoes characteristic changes, transitioning from pattern A (a triple-line pattern comprising a central hyper-echoic line surrounded by two hypoechoic layers) to pattern B (an intermediate isoechogenic pattern with similar reflectivity as the surrounding myometrium and a poorly defined central echogenic line), and finally to pattern C (a homogeneous, hyperechogenic endometrium). Numerous published studies have examined the correlation between endometrial patterns and outcomes of assisted reproductive techniques, yielding conflicting conclusions(\u003cspan additionalcitationids=\"CR26 CR27 CR28\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo date, limited research has been conducted to investigate the potential correlation between changes in endometrial thickness in response to progesterone and neonatal outcomes. This study aims to analyze the variation in endometrial thickness (from the day of embryo transfer to the day prior to progesterone administration) and explore its impact on neonatal outcomes within FET cycles.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and patients\u003c/h2\u003e \u003cp\u003eThis retrospective study was conducted at the Department of Assisted Reproduction, Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine (Shanghai, China), involving a cohort of 6331 women who underwent frozen embryo transfer (FET) cycles between January 2010 and December 2019 in our center. The inclusion criteria encompassed women aged\u0026thinsp;\u0026le;\u0026thinsp;40 years with a body mass index (BMI)\u0026thinsp;\u0026lt;\u0026thinsp;30 kg/m\u003csup\u003e2\u003c/sup\u003e who received FET cycles in our center and had embryo transfer on day 3. Exclusion criteria comprised women with uterine malformation, endometriosis, adenomyosis, as well as endometrial polyps or submucosal myomas identified through hysteroscopy that could potentially impact embryo implantation. This observational study obtained approval from the Ethics Committee (Institutional Review Board) of Shanghai Ninth People's Hospital without any intervention. This study adhered to the principles outlined in the Helsinki Declaration.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eTreatment protocol\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eTreatment protocol\u003c/div\u003e \u003cp\u003eEndometrial preparation for frozen embryo transfer (FET) involved both artificial cycles (estrogen-progesterone cycle, EP) and natural cycles (NCs). In the NC group, all patients underwent ultrasonic evaluation starting from day 10 of their menstrual cycle. The endometrial thickness (EMT) and mean diameter of the dominant follicle were assessed by the same physician. Once the diameter of the dominant follicle reached approximately 18mm and EMT reached 7mm, a blood sample was collected to measure progesterone, estradiol (E\u003csub\u003e2\u003c/sub\u003e), and luteinizing hormone (LH) levels. If the E2 level exceeded 150 pg/mL while progesterone remained below 1 ng/mL, one of two procedures was conducted based on serum LH values: if LH was less than 20 mIU/mL, a bolus dose of 5,000 IU human chorionic gonadotropin (hCG) was administered on the same night; three days later, progesterone supplementation commenced. Finally, five days after hCG injection, cleavage-stage embryos were transferred. In cases where the serum LH concentration was \u0026ge;\u0026thinsp;20 mIU/mL, hCG administration took place on the same afternoon followed by progesterone administration after a two-day interval. The transfer of cleavage-stage embryos occurred four days later. The evaluation of endometrial thickness (EMT) on the day of hCG administration was documented using transvaginal ultrasound imaging.\u003c/p\u003e \u003cp\u003eFor EP cycles, patients initiated sequential oral administration of micronized estradiol (8mg/day) on cycle day 3. EMT ultrasound measurement was conducted 12\u0026ndash;14 days after the initiation of micronized estradiol. Progesterone supplementation commenced when EMT reached 7mm. Patients initiated oral administration of yellow Fematon tablets, twice daily at a dosage of two tablets, each containing 2 mg micronized estradiol and 10 mg dydrogesterone (Abbott Healthcare Products B.V.). Additionally, soft vaginal P capsules were administered twice daily at a dosage of 200 mg each (Laboratoires Besins International). EMT on the day prior to progesterone administration was also documented through transvaginal ultrasound. Embryos were warmed and transferred on day 3 following P supplementation, with a maximum limit of two embryos for transfer.\u003c/p\u003e \u003cp\u003ePlease refer to previous studies for comprehensive information regarding the endometrial preparation process for frozen embryo transfer (FET) and the measurement method of endometrial thickness (EMT)(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eEMT assessment\u003c/h3\u003e\n\u003cp\u003eBased on variations in EMT measurements between the day of embryo transfer and the day prior to progesterone administration, the patients were categorized into three distinct groups: individuals exhibiting a decline in EMT levels (Group 1), those with stable EMT values (Group 2), and subjects displaying an increase in EMT levels (Group 3).\u003c/p\u003e \u003cp\u003eAll ultrasound measurements were conducted by a senior technician utilizing the GE Voluson E8 (GE Healthcare, Austria). EMT was determined as the maximum distance between the endometrial-myometrial interface in the mid-sagittal plane, following our previously established methodology(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). In NCs, the assessment of endometrial thickness before progesterone administration commenced from the day of human chorionic gonadotropin (hCG) administration. Conversely, in EP cycles, this evaluation was conducted based on the final ultrasound prior to initiating progesterone administration. Additionally, for all patients, transvaginal ultrasound was performed on the morning of embryo transfer to ensure exclusion of any endometrial cavity fluid or other unfavorable conditions that could impede successful embryo transfer.\u003c/p\u003e\n\u003ch3\u003eOutcome measures and definitions\u003c/h3\u003e\n\u003cp\u003eLive birth was defined as the delivery of a viable neonate after 24 or more weeks of gestation. In frozen cycles, gestational age (GA) was calculated from the day of embryo transfer, which was designated as Day 17 due to cryopreservation on Day 3(\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). Preterm birth and very preterm birth were defined as delivery occurring prior to 37 and 32 completed gestational weeks, respectively. Small for gestational age (SGA) and very small for gestational age (VSGA) were defined as birthweight falling below the 10th and 3rd percentiles for the corresponding gestational age, respectively. Large for gestational age (LGA) was defined as birth weight exceeding the 90th percentile for the given gestational age, while very large for gestational age (VLGA) was defined as birthweight surpassing the 97th percentile. Low birthweight (LBW), very low birthweight (VLBW), high birthweight (HBW), and very high birth weight (VHBW) were classified as having a birthweight less than 2500g, less than 1500g, greater than 4000g, and greater than 4500g, respectively. In addition, the Z-score was utilized to compute birthweight adjusted for gestational age and neonatal gender using the following formula: Z-score= (x\u0026thinsp;\u0026minus;\u0026thinsp;\u0026micro;)/σ, where x represents the weight of an infant, \u0026micro; denotes the mean birthweight for infants of the same sex and gestational age in the reference group, and σ signifies the standard deviation of the reference group. Birthweight percentiles as well as Z-score calculation were based on Chinese singleton newborns from a reference population stratified by neonatal gender and gestational age(\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Data regarding pregnancy and neonatal outcomes were extracted from electronic medical records.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe baseline characteristics and neonatal outcomes were compared using one-way analysis of variance for continuous data, while χ\u003csup\u003e2\u003c/sup\u003e or Fisher's exact tests were employed for categorical data, as deemed appropriate. Multivariable logistic regression analysis was conducted to identify any associations between changes in EMT and neonatal outcomes, while multiple linear regression was employed to investigate the independent impact of EMT change on birthweight. The following confounding factors were included in all multivariable analyses: maternal age and body mass index (BMI), paternal age, parity, duration of infertility, previous small-for-gestational-age (SGA) infants, number of embryos transferred, type of endometrial preparation, rank of frozen embryo transfer cycle, pregnancy complications such as gestational diabetes, hypertension, pre-eclampsia and placenta previa), newborn gender and gestational age at birth. The reference group for comparison was the stable EMT group. Statistical significance was defined as a p-value less than 0.05. All data were analyzed using the Statistical Package for the Social Sciences for Windows (SPSS version 25.0).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eIn this observational study, the final dataset comprised 6331 women who met the inclusion criteria, with no loss to follow-up. The baseline demographic and cycle characteristics of all patients are presented in Table\u0026nbsp;1 based on EMT changes. Among all FET cycles, EMT decreased in 1746 patients and increased in 2835 patients on the day of embryo transfer. Comparison among the three groups did not reveal any significant differences for maternal age and BMI, paternal age, infertility cause, previous SGA babies, or FET cycle rank. However, parity, infertility duration, FET endometrial preparation, and number of embryos transferred differed significantly across EMT change categories. Neonatal outcomes stratified by changes in EMT status are also presented in Table I and Table II. There were no significant differences observed across the three groups in terms of newborn gender, distribution of gestational age, and occurrence of pregnancy-related complications. Similarly, the mean birthweight did not significantly differ among the three groups (3355.30\u0026thinsp;\u0026plusmn;\u0026thinsp;502.69g vs. 3351.30\u0026thinsp;\u0026plusmn;\u0026thinsp;474.79 vs. 3344.26\u0026thinsp;\u0026plusmn;\u0026thinsp;514.54, P\u0026thinsp;=\u0026thinsp;0.753). However, when considering the mean birthweight Z-scores categorized by EMT changes, a significant variation was noted between groups: Group 3 exhibited lower Z-scores (0.34\u0026thinsp;\u0026plusmn;\u0026thinsp;1.07) compared to Group 1 (0.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04) and Group 2 (0.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04), with statistical significance at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eGiven the significance of gestational age at delivery as a crucial factor in determining newborn birthweight, we conducted a subgroup analysis by stratifying term (\u0026ge;\u0026thinsp;37 weeks) or preterm births (\u0026lt;\u0026thinsp;37 weeks). As depicted in Table III and Table IV, there was no statistically significant disparity observed in the mean birthweight of singletons among the three groups within the term (\u0026ge;\u0026thinsp;37 weeks) category. Compared to the stable group of EMT, the incidence rates of low birth weight (LBW) and small for gestational age (SGA) in term infants were 1.1% (adjusted odds ratio [aOR]: 1.645, 95% confidence interval [CI]: 0.818\u0026ndash;3.307) and 2.7% (aOR: 1.141, 95% CI:0.783\u0026ndash;1.662), respectively, in the decreased EMT group; however, there was no significant association between the increased EMT group and risks of LBW (aOR: 1.310, 95% CI:0.723\u0026ndash;2.375) or SGA (aOR:0.912, 95% CI:0.660\u0026ndash;1.261). In singletons delivered before \u0026lt;\u0026thinsp;37 weeks of gestation, Group 2 exhibited a statistically significant increase in mean birthweight compared to the other two groups (P\u0026thinsp;=\u0026thinsp;0.025) for preterm infants. The incidence of LBW in preterm infants was highest in Group 3, however, there were no statistically significant differences observed among the three groups. It is noteworthy that Group 3 exhibited the highest occurrence of SGA preterm infants (aOR: 0.893, 95% CI: 0.090\u0026ndash;8.898).\u003c/p\u003e \u003cp\u003eMultiple linear regression analyses were conducted to examine the association between change in EMT and birthweight (Table V). Even after adjusting for various potential confounders, any alteration in EMT following progesterone administration did not have a statistically significant impact on newborns' birthweight. Furthermore, newborn gender (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and gestational age (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) independently served as predictors for birthweight.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective analysis of 6331 live-born singletons, we present the initial evidence indicating that any alteration in EMT subsequent to progesterone administration does not exert a significant impact on the birthweight of newborns in frozen embryo transfer (FET) cycles. Neither a decrease nor an increase in EMT following progesterone administration is associated with elevated risks of PTB, LBW, SGA, or pregnancy-related complications in term infants. Upon adjusting for several potential confounders, both newborn gender (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and gestational age (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) emerge as independent predictors of birthweight.\u003c/p\u003e \u003cp\u003eIn recent decades, considerable attention has been devoted to investigating the impact of EMT on the success rates of in vitro fertilization (IVF). Numerous studies have consistently demonstrated that a thin endometrial lining exerts an adverse influence on pregnancy outcomes(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). Limited research has been dedicated to exploring the potential association between EMT and neonatal birthweight. In the initial investigation conducted by Chung et al., they examined various factors influencing adverse perinatal outcomes in pregnancies following IVF treatment, revealing a twofold increased risk of adverse perinatal outcome in individuals with EMT\u0026thinsp;\u0026le;\u0026thinsp;10 mm compared to those with EMT\u0026thinsp;\u0026gt;\u0026thinsp;12 mm(OR: 2.04; 95% CI: 1.09\u0026ndash;3.83)(\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). Additionally, a significant protective effect on infant outcome was observed with an increase in endometrial thickness (OR: 0.89; 95% CI: 0.80\u0026ndash;0.99). Specifically, for every millimeter decrease in endometrial thickness, there was a relative increase of 12% (1/0.89\u0026thinsp;=\u0026thinsp;1.12) in the risk of adverse perinatal outcomes(\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). However, no statistically significant difference in risk was observed when the analysis was limited to singletons (aOR: 1.66, 95% CI: 0.73\u0026ndash;3.81)(\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e). Another study revealed a positive correlation between EMT administered on the day of HCG trigger and neonatal birthweight, particularly in pregnancies complicated by obstetric factors(\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). The study also revealed that the increase in EMT no longer exhibited a significant association with birth weight in uncomplicated pregnancies(\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Oron et al. demonstrated that an endometrial thickness of less than 7.5 mm was associated with a significantly increased risk for adverse obstetric outcomes (adjusted OR: 1.53; 95% CI: 1.03\u0026ndash;2.42; P\u0026thinsp;=\u0026thinsp;0.04). However, no significant difference in singleton live birth weight was observed(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Du et al. demonstrated that an EMT\u0026thinsp;\u0026le;\u0026thinsp;7.5 mm was significantly associated with an elevated risk of LBW in 2,847 singletons resulting from fresh cycles (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). In a recent large-scale retrospective study involving 5,220 singleton newborns, it was observed that individuals with an endometrial thickness (EMT) of less than 8 mm had an adjusted odds ratio (aOR) of 1.57 (95% CI: 1.09\u0026ndash;2.26) for low birth weight (LBW) in frozen embryo transfer (FET) cycles(\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). This finding is consistent with previous research conducted at our center (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn most of the aforementioned studies, EMT was assessed during the proliferative phase prior to progesterone administration. However, it is important to note that endometrial development exhibits distinct physiological characteristics between the follicular and luteal phases. During the follicular phase, estrogen exerts its influence on the endometrium, promoting EMT and facilitating the linear growth of both endometrial glands and blood vessels(\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Under the influence of progesterone, endometrial proliferation ceases within 2\u0026ndash;3 days after ovulation(\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Limited research has been conducted on the association between changes in EMT following progesterone administration and pregnancy as well as neonatal outcomes.\u003c/p\u003e \u003cp\u003eAlthough a limited number of studies have assessed the changes in EMT during IVF stimulation(\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan additionalcitationids=\"CR42\" citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e), their findings exhibit some conflicting conclusions. The prognostic utility of the EMT change, occurring between the third day of gonadotrophin stimulation and the day of hCG administration, in predicting pregnancy occurrence was reported to be insignificant by Zhao et al. Furthermore, their findings indicated that a combined assessment of EMT change and type failed to accurately predict clinical outcomes(\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). However, unfortunately, they neglected to investigate the correlation between changes in EMT following progesterone administration and the subsequent pregnancy and neonatal outcomes. Haas, J. et al. investigated the disparity in EMT between the late estrogen phase and the day of embryo transfer in 274 FET cycles, revealing a robust inverse correlation of high significance between pregnancy outcomes and changes in EMT(\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). However, there were several limitations in their study. Firstly, the EMT was assessed using different measurement methods: transabdominal ultrasound on the day of embryo transfer and vaginal ultrasound at the end of the estrogen phase. Secondly, only women undergoing the hormonal preparation protocol for the FET cycle were included. Lastly, they solely focused on evaluating ongoing pregnancy rates in the FET cycle and did not investigate any potential association between changes in EMT after progesterone administration and neonatal outcomes. Another study reported that an increased endometrial thickness following progesterone administration was associated with improved pregnancy outcomes(\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). However, the relationship between changes in EMT after progesterone administration and neonatal outcomes was not investigated. Our previous study demonstrated that irrespective of any changes in epithelial-mesenchymal transition (EMT) following progesterone administration, there was no significant impact on the clinical pregnancy rate (CPR) and live birth rate during the frozen embryo transfer (FET) cycle(\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). However, our previous investigation did not explore the association between EMT alterations after progesterone administration and neonatal outcomes.\u003c/p\u003e \u003cp\u003eThe present study, aimed at addressing the limitations of previous investigations, examined the precise impact of progesterone administration on EMT change and its association with neonatal outcomes in FET cycles. Our findings, based on a cohort of over 6000 singleton newborns conceived through FET cycles, unequivocally demonstrate that any alteration in EMT following progesterone administration does not exert a significant impact on the outcomes of term newborns in FET cycles. In this study, results from multiple linear regression analysis revealed that both newborn gender and gestational age independently predicted birthweight, which is consistent with existing literature(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e). Male neonates have been predicted to weigh 130g higher than female neonates. Each weekly increase in gestational age has been associated with a 172g rise in birthweight. To account for potential bias related to infant gender and gestational age, Z-scores were calculated and compared across the three groups, revealing consistently lower scores in Group 3. In our cohort, significant differences were observed among the three groups regarding baseline and cycle characteristics such as parity, infertility duration, FET endometrial preparation, and number of embryos transferred. However, based on the linear regression model analysis, these aforementioned confounders did not exert any influence on neonatal birthweight. Moreover, considering that pregnancy outcomes may impact birthweight, we conducted additional analyses both including and excluding this factor; nevertheless, consistent results were obtained.\u003c/p\u003e \u003cp\u003eSeveral limitations were encountered in this study. Despite our meticulous review of the database using strict inclusion and exclusion criteria, the retrospective design constrained our findings. Additionally, to mitigate potential confounding effects of culture duration on FET outcomes, we focused exclusively on neonatal outcomes following day 3 embryo transfers(\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e). A major strength of this study was the use of data from a single center, ensuring consistency in practice. Endometrial preparation protocols were highly consistent throughout the study period, and endometrial thickness measurements were conducted by the same doctor at our center. While there may have been some bias due to inter-observer variability or changes over time in measurement methods, we accounted for potential confounders that could have impacted our findings.\u003c/p\u003e"},{"header":"Conclusions and Future Prospects","content":"\u003cp\u003eThe present large-scale single-center study provides valuable insights into the impact of progesterone administration-induced EMT changes on pregnancy outcomes in frozen embryo transfer (FET) cycles. Our findings indicate that any alterations in EMT following progesterone administration do not significantly affect the outcomes of term newborns in FET cycles. This novel discovery offers reassuring information for patients undergoing FET with EMT changes due to progesterone administration, regarding the health of their neonates. However, further prospective cohort studies with extended follow-up periods are warranted to validate these conclusions.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eEMT\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEndometrial Thickness\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eFET\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFrozen-thawed Embryo Transfer\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eIVF\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eIn vitro Fertilization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eART\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAssisted Reproductive Technology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eSGA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSmall Gestational Age\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eVSGA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVery small for Gestational Age\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eLGA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLarge for Gestational Age\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eVLGA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVery Large for Gestational Age\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eLBW\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLow Birthweight\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eVLBW\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVery Low Birthweight\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eHBW\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHigh Birthweight\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eVHBW\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVery High Birthweight\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003ePTB\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePreterm Birth\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis observational study obtained approval from the Ethics Committee (Institutional Review Board) of Shanghai Ninth People's Hospital without any intervention. This study adhered to the principles outlined in the Helsinki Declaration. Written informed consent was waived due to the retrospective study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China (grant numbers：82271732, 82001502) and Shanghai Science and Technology Innovation Fund (grant numbers: 22Y21900800).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions Statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKYP and CQJ provided overall supervision for the study, including overseeing procedures, conception, design, and completion. YS, ZYW, GHY and LYL were responsible for data collection. YJ, ZJ, and DT contributed to data analysis and manuscript drafting. YJ, ZJ, and DT made equal contributions to this article. All authors participated in the final interpretation of study data and revisions of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors express their gratitude to the nurses and laboratory staff of the Department of Assisted Reproduction for their invaluable contributions to this research. Additionally, the authors extend their appreciation to the infertile couples who willingly participated in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBerntsen SS-AV, Wennerholm UB, Laivuori H, Loft A, Oldereid NB, Romundstad LB, Bergh C, Pinborg A. The health of children conceived by ART: 'the chicken or the egg?'. Hum Reprod Update. 2019;25(2):137\u0026ndash;58.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUB AP, LB W, K A RAL, V S-A, et al. Why do singletons conceived after assisted reproduction technology have adverse perinatal outcome? Syst Rev meta-analysis. 2013;19(2):87\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCai J, Liu L, Xu Y, Liu Z, Jiang X, Li P, et al. Supraphysiological estradiol level in ovarian stimulation cycles affects the birthweight of neonates conceived through subsequent frozen-thawed cycles: a retrospective study. BJOG. 2019;126(6):711\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePJ NPRTE, AC C. P, K H, JP L, Supraphysiologic estradiol is an independent predictor of low birth weight in full-term singletons born after fresh embryo transfer. 2017;32(7):1410\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGD R, K K, JM C, BJ Y, RJ C et al. AH D, Are intracytoplasmic sperm injection and high serum estradiol compounding risk factors for adverse obstetric outcomes in assisted reproductive technology? 2016;106(2):363\u0026thinsp;\u0026ndash;\u0026thinsp;70.e3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBS S, ST D. CE B, FC G. Comparison of birth weights in patients randomly assigned to fresh or frozen-thawed embryo transfer. 2016;106(2):317\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eH Z, AP VM. reproduction DJJH. Does the type of culture medium used influence birthweight of children born after IVF? 2015;30(3):530\u0026thinsp;\u0026ndash;\u0026thinsp;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeltran Anzola A, Pauly V, Riviere O, Sambuc R, Boyer P, Vendittelli F et al. Birthweight of IVF children is still a current issue and still related to maternal factors. 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Endometrial thickness and pregnancy rates after IVF: a systematic review and meta-analysis. Hum Reprod Update. 2014;20(4):530\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaged AM, Kamel AM, Abu-Hamila F, Elkomy RO, Ohida OA, Hassan SM et al. The measurement of endometrial volume and sub-endometrial vascularity to replace the traditional endometrial thickness as predictors of in-vitro fertilization success. Gynecol Endocrinol. 2019:1\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang T, Li Z, Ren X, Huang B, Zhu G, Yang W, et al. Endometrial thickness as a predictor of the reproductive outcomes in fresh and frozen embryo transfer cycles: A retrospective cohort study of 1512 IVF cycles with morphologically good-quality blastocyst. Med (Baltim). 2018;97(4):e9689.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOron G, Hiersch L, Rona S, Prag-Rosenberg R, Sapir O, Tuttnauer-Hamburger M, et al. 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Front Endocrinol. 2022;13:929617.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang J, Lin J, Lu X, Gao H, Song N, Cai R, et al. Association between endometrial thickness and neonatal outcomes in intrauterine insemination cycles: a retrospective analysis of 1,016 live-born singletons. Reprod Biol Endocrinol. 2020;18(1):48.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang J, Liu H, Mao X, Chen Q, Si J, Fan Y, et al. Effect of endometrial thickness on birthweight in frozen embryo transfer cycles: an analysis including 6181 singleton newborns. Hum Reprod. 2019;34(9):1707\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu KE, Hartman M, Hartman A, Luo ZC, Mahutte N. The impact of a thin endometrial lining on fresh and frozen\u0026ndash;thaw IVF outcomes: an analysis of over 40 000 embryo transfers. Hum Reprod. 2018;33(10):1883\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAC F, DE P, GA LAB, AL T. Sonographic depiction of endometrial changes occurring with ovulation induction. J Ultrasound Med. 1984;3(8):341\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS B. Changes in endometrial thickness, width, length and pattern in predicting pregnancy outcome during ovarian stimulation in in vitro fertilization. 2001;18(3):258\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGonen Y, Casper RF, Jacobson W, Blankier J. Endometrial thickness and growth during ovarian stimulation: a possible predictor of implantation in in vitro fertilization. Fertil Steril. 1989;52(3):446\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen SL, Wu FR, Luo C, Chen X, Shi XY, Zheng HY, et al. 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Combined analysis of endometrial thickness and pattern in predicting clinical outcomes of frozen embryo transfer cycles with morphological good-quality blastocyst: A retrospective cohort study. Med (Baltim). 2018;97(2):e9577.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu H, Zhang J, Wang B, Kuang Y. Effect of endometrial thickness on ectopic pregnancy in frozen embryo transfer cycles: an analysis including 17,244 pregnancy cycles. Fertil Steril. 2019;113(1):9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe J, Zhang J, Gao H, Zhu Y, Wang Y, Cai R, et al. Effect of Endometrial Thickness Change in Response to Progesterone Administration on Pregnancy Outcomes in Frozen-Thawed Embryo Transfer: Analysis of 4465 Cycles. Front Endocrinol. 2020;11:546232.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEC N, AP VM, JP ECJGD. G, LJ S, Further evidence that culture media affect perinatal outcome: findings after transfer of fresh and cryopreserved embryos. 2012;27(7):1966\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang J, Li X, Dai L, Zeng W, Li Q, Li M, et al. The changes in maternal mortality in 1000 counties in mid-Western China by a government-initiated intervention. PLoS ONE. 2012;7(5):e37458.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-Toukhy T, Coomarasamy A, Khairy M, Sunkara K, Seed P, Khalaf Y, et al. The relationship between endometrial thickness and outcome of medicated frozen embryo replacement cycles. Fertil Steril. 2008;89(4):832\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVC R, S S-R, N DM PD, NP P. V S, Should we continue to measure endometrial thickness in modern-day medicine? The effect on live birth rates and birth weight. 2018;36(4):416\u0026ndash;26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC KC, SJ CRCKL, AJ R. C, Factors influencing adverse perinatal outcomes in pregnancies achieved through use of in vitro fertilization. 2006;86(6):1634\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC RMSBASMDG. DG. Endometrial thickness influences neonatal birth weight in pregnancies with obstetric complications achieved after fresh IVF-ICSI cycles. 2017;296(1):115\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu M, Zhang J, Liu M, Guan Y, Wang X. Endometrial Thickness Is a Risk Factor for Singleton Low Birth Weight From Single Blastocyst Transfer: A Retrospective Cohort Study. Front Endocrinol. 2021;12:730512.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu K, Kawai A, Hunt S, Li W, Li X, Zhang R, et al. Endometrial thickness in the prediction of neonatal adverse outcomes in frozen cycles for singleton pregnancies. Reprod Biomed Online. 2021;43(3):553\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang J, Lin J, Xia L, Tian L, Xu D, Liu P, et al. Decreased Endometrial Thickness Is Associated With Higher Risk of Neonatal Complications in Women With Polycystic Ovary Syndrome. Front Endocrinol. 2021;12:766601.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaas J, Smith R, Zilberberg E, Nayot D, Meriano J, Barzilay E et al. Endometrial compaction (decreased thickness) in response to progesterone results in optimal pregnancy outcome in frozen-thawed embryo transfers. Fertil Steril. 2019.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBu Z, Yang X, Song L, Kang B, Sun Y. The impact of endometrial thickness change after progesterone administration on pregnancy outcome in patients transferred with single frozen-thawed blastocyst. Reprod Biol Endocrinol. 2019;17(1):99.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcWilliams GD, Frattarelli JL. Changes in measured endometrial thickness predict in vitro fertilization success. Fertil Steril. 2007;88(1):74\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin S, Li M, Lian Y, Chen L, Liu P. No effect of embryo culture media on birthweight and length of newborns. Hum Reprod. 2013;28(7):1762\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNelissen EC, Van Montfoort AP, Coonen E, Derhaag JG, Geraedts JP, Smits LJ, et al. Further evidence that culture media affect perinatal outcome: findings after transfer of fresh and cryopreserved embryos. Hum Reprod. 2012;27(7):1966\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQ JZYWHLXM. C, Y F, Effect of in vitro culture period on birth weight after vitrified-warmed transfer cycles: analysis of 4,201 singleton newborns. 2019;111(1):97\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable I Baseline demographics, cycle characteristics and perinatal outcomes according to endometrial thickness change.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup1\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1746)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup2\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1750)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup3\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=2835)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eMaternal age (y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e31.82\u0026plusmn;3.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e31.66\u0026plusmn;3.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e31.66\u0026plusmn;3.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.329\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eMaternal BMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e21.58\u0026plusmn;2.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e21.53\u0026plusmn;2.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e21.54\u0026plusmn;3.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.854\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003ePaternal age (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e33.92\u0026plusmn;5.03\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e33.79\u0026plusmn;4.85\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e33.71\u0026plusmn;4.93\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.361\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eInfertility cause\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 350px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.142\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e977(56.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1006(57.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1540(54.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e252(14.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e263(15.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e428(15.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e367(21.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e316(18.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e608(21.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eUnexplained\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e150(8.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e165(9.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e259(9.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eParity, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 350px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.000\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eFirst\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e874(50.1)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;941(53.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1593(56.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;High order\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e872(49.9)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;809(46.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1242(43.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eInfertility duration (y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e3.64\u0026plusmn;2.67\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e4.03\u0026plusmn;2.78\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3.65\u0026plusmn;2.65\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.000\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 482px;\"\u003e\n \u003cp\u003eFET cycle rank, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.185\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;First\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1097(62.8)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1130(64.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1857(65.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;High order\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e649(37.2)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e620(35.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e978(34.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 482px;\"\u003e\n \u003cp\u003eFET endometrial preparation, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.000\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;Ovulatory cycle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1110(63.6)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1156(66.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1962(69.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;Artificial cycle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e636(36.4)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e594(33.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e873(30.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 482px;\"\u003e\n \u003cp\u003eNumber of embryos transferred, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.029\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e150(8.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e164(9.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e205(7.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1596(91.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1586(90.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2630(92.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003ePrevious SGA newborns, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e8(0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3(0.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e11(0.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.314\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 482px;\"\u003e\n \u003cp\u003eNewborn gender, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.599\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e852(48.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e866(49.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1360(48.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e894(51.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e884(50.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1475(52.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 482px;\"\u003e\n \u003cp\u003eGestational age (weeks) , n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.367\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u0026lt;37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e129(7.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;110(6.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e184(6.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026ge;37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1617(92.6)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1640(93.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2651(93.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003ePregnancy-related complications\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e156(8.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e173(9.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e238(8.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.229\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eBirth weight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e3355.30\u0026plusmn;502.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3351.30\u0026plusmn;474.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3344.26\u0026plusmn;514.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.753\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eZ-score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.43\u0026plusmn;1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.38\u0026plusmn;1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.34\u0026plusmn;1.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e0.023\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eSGA - small for gestational age. \u003csup\u003ea\u003c/sup\u003eOne-way ANOVA. Values are mean\u0026plusmn;SD. \u003csup\u003eb\u003c/sup\u003ePearson chi-square test. Values are number (percentage). \u003csup\u003ec\u003c/sup\u003eFisher\u0026rsquo;s exact test. Values are number (percentage). Z-score: EMT increase group vs EMT decrease group (P=0.007).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable II Birth weights and birth weights categories of live born singletons\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup1\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1746)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup2\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1750)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup3\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=2835)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 490px;\"\u003e\n \u003cp\u003eNewborn gender, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.599\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u0026nbsp;Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e852(48.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e866(49.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e1360(48.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u0026nbsp;Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e894(51.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e884(50.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e1475(52.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eMean birthweight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e3355.30\u0026plusmn;502.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e3351.30\u0026plusmn;474.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e3344.26\u0026plusmn;514.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.753\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eNormal weight, 2500\u0026ndash;4000 g, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e1513(86.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e1550(88.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e2476(87.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.070\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eLBW (\u0026lt; 2500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e64(3.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e63(3.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e105(3.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eHBW (\u0026gt; 4000 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e145(8.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e110(6.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e201(7.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eVHBW (\u0026gt; 4500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e15(0.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e23(1.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e29(1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eVLBW (\u0026lt; 1500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e9(0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e4(0.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e24(0.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eVery small for gestational age (\u0026lt;3rd percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e26(1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e33(1.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e49(1.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.133\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eSmall for gestational age (\u0026lt;10th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e47(2.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e55(3.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e111(3.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eNormal gestational age (\u0026ge;10th percentile, \u0026le;90th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e1327(76.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e1364(77.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e2177(76.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eLarge for gestational age (\u0026gt;90th percentile)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e242(13.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e212(12.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e334(11.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003eVery large for gestational age (\u0026gt;97th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 91px;\"\u003e\n \u003cp\u003e104(6.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e86(4.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e164(5.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eSGA - small for gestational age. LBW, low birth weight; VLBW, very low birth weight; HBW, high birth weight; VHBW, very high birth weight\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea\u003c/sup\u003eOne-way ANOVA. Values are mean\u0026plusmn;SD. \u003csup\u003eb\u003c/sup\u003ePearson chi-square test. Values are number (percentage).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eValues are number (percentage). Z-score: EMT increase group vs EMT decrease group (P=0.007).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable III Birth weights and birth weights categories of live born singletons by gestational age.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"619\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 557px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGestational age\u0026ge;37 weeks\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1617\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1640\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2651\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eNewborn gender, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.505\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003e\u0026nbsp;Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e788(48.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e817(49.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1272(48.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003e\u0026nbsp;Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e829(51.3)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e823(50.2)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1379(52.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eMean birthweight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e3423.65\u0026plusmn;424.872\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3400.65\u0026plusmn;418.856\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e3410.05\u0026plusmn;423.527\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.294\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eNormal weight, 2500\u0026ndash;4000 g, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1439(89.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1485(90.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2390(90.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.222\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eLBW (\u0026lt; 2500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e18(1.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e24(1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e32(1.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eHBW (\u0026gt; 4000 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e145(9.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e109(6.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e200(7.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVHBW (\u0026gt; 4500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e15(0.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e22(1.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e29(1.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVery small for gestational age (\u0026lt;3rd percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e23(1.4)\u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e28(1.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e42(1.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.807\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eSmall for gestational age (\u0026lt;10th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e44(2.7)\u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e49(3.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e91(3.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.402\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eLarge for gestational age (\u0026gt;90th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e230(14.2)\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e204(12.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e323(12.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.096\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVery large for gestational age (\u0026gt;97th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e103(6.4)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e80(4.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e147(5.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.178\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 557px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGestational age \u0026lt; 37 weeks\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eN\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e129\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e184\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eNewborn gender, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 366px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.732\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003e\u0026nbsp;Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e64(49.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e49(44.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e88(47.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003e\u0026nbsp;Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e65(50.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e61(55.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e96(52.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eMean birthweight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e2498.57\u0026plusmn;605.965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2615.59\u0026plusmn;629.418\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e2396.39\u0026plusmn;732.408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.025\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eNormal weight, 2500\u0026ndash;4000 g, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e74(57.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e65(59.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e86(46.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.067\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVLBW (\u0026lt; 1500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e9(7.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e4(3.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e24(13.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eLBW (\u0026lt; 2500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e46(35.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e39(35.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e73(39.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eHBW (\u0026gt; 4000 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0(0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1(0.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1(0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVHBW (\u0026gt; 4500 g), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0(0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1(0.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0(0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eVery small for gestational age (\u0026lt;3rd percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e3(2.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e5(4.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e7(3.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.632\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 192px;\"\u003e\n \u003cp\u003eSmall for gestational age (\u0026lt;10th percentile), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e6(4.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e11(10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e27(14.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.017\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eLBW, low birth weight; VLBW, very low birth weight; HBW, high birth weight; VHBW, very high birth weight\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea\u003c/sup\u003eOne-way ANOVA. Values are mean\u0026plusmn;SD.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003eb\u003c/sup\u003ePearson chi-square test. Values are number (percentage). \u003csup\u003ec\u003c/sup\u003eFisher\u0026rsquo;s exact test. Values are number (percentage).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable IV Crude and adjusted ORs for birth weights and birthweights categories in singleton births by gestational age.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGestational age\u0026ge;37 weeks\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVery small for gestational age (\u0026lt;3rd percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.204(0.690-2.099)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.079(0.666-1.748)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.368(0.732-2.554)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.064(0.619-1.827)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSmall for gestational age (\u0026lt;10th percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.140(0.815-1.593)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.933(0.700-1.244)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.141(0.783-1.662)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.912(0.660-1.261)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLarge for gestational age (\u0026gt;90th percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\u0026nbsp;\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\u0026nbsp;\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\u0026nbsp;\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.808(0.677-0.963)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.972(0.826-1.143)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.822(0.676-1.000)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.950(0.793-1.138)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVery large for gestational age (\u0026gt;97th percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.754(0.558-1.018)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.766(0.550-1.067)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.874(0.661-1.155)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.848(0.624-1.154)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLow birth weight(\u0026lt;2500g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.319(0.713-2.440)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.216(0.713-2.071)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.645(0.818-3.307)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.310(0.723-2.375)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh birth weight (\u0026gt;4000g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.791(0.621-1.007)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.918(0.734-1.149)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.784(0.600-1.025)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.872(0.680-1.117)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVery high birth weight (\u0026gt;4500g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.452(0.751-2.809)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.229(0.704-2.147)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e1.679(0.805-3.502)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e1.200(0.653-2.204)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGestational age \u0026lt; 37 weeks\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSmall for gestational age (\u0026lt;10th percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e2.278(0.814-6.376)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.646(0.307-1.361)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e9.992(0.587-17.227)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.893(0.090-8.898)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLow birth weight(\u0026lt;2500g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eCrude OR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.864(0.514-1.450)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.576(0.356-0.930)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 37.4322%;\"\u003e\n \u003cp\u003eAOR (95% CI)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.0506%;\"\u003e\n \u003cp\u003e0.895(0.195-4.104)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15.3707%;\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 23.1465%;\"\u003e\n \u003cp\u003e0.087(0.019-0.388)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCI: confidence interval, OR: odds ratio, AOR: adjusted odds ratio\u003c/p\u003e\n\u003cp\u003eAnalyses were adjusted for maternal age and BMI, paternal age, infertility cause, parity, infertility duration, FET cycle rank, the type of endometrial preparation, number of embryos transferred, newborn sex, previous SGA newborns.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable V Results of multiple linear regression analysis on the birthweight of live-born singletons\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"553\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"bottom\" style=\"width: 206px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eModel\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 138px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNon-standardized coefficients\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStandardized coefficients\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003et\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eB\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStd. error\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBeta\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eConstant\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-3335.343\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e146.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-22.833\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eFET cycle rank, High order\u0026nbsp;(vs First)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e6.485\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e10.922\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.006\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.594\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.553\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eMaternal age (y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e1.986\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.954\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003ePaternal age (y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e0.179\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e1.484\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.121\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.904\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eDuration of infertility(y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-3.046\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e2.054\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-1.483\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.138\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eParity, High order（vs First )\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-8.629\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e10.794\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-0.799\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.424\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eMaternal BMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-0.655\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e1.767\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-0.370\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.711\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eFET endometrial preparation, Artificial cycle (vs Ovulatory cycle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-12.873\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e11.218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-1.148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.251\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eEMT: before progesterone administration (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e9.462\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e4.925\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.041\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e1.921\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.055\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eEMT: on the day of FET (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-10.407\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e4.545\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.051\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-2.290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eEMT change\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eRemain stable(reference)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eIncreased\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-22.158\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e15.251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-1.453\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.146\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eDecreased\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e1.561\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e15.245\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.102\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.918\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eNo. of embryo transferred\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e5.084\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e18.880\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e0.269\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.788\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003ePregnancy-related complications, yes (vs no)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e-23.406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e19.387\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-0.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e-1.207\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.227\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eInfant gender boys (vs girls)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e130.122\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e10.362\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e12.558\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 206px;\"\u003e\n \u003cp\u003eGestational age (weeks)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e172.641\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e3.275\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e52.707\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"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":"Birthweight, frozen-thawed embryo transfer, endometrial thickness change, Neonatal outcomes","lastPublishedDoi":"10.21203/rs.3.rs-5278874/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5278874/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eTo assess the impact of progesterone-induced changes in endometrial thickness (EMT) on singleton infant outcomes during frozen-thawed embryo transfer (FET) cycles.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis retrospective observational study included a total of 6331 singleton live births resulting from frozen-thawed Day 3 embryo transfer. Endometrial thickness (EMT) was assessed using transvaginal ultrasound one day prior to progesterone administration and on the day of frozen embryo transfer (FET) to examine any variations in EMT. The study population comprised 6331 women, who were categorized into three groups based on changes in EMT: the EMT increase group, the EMT decrease group, and the EMT stable group. The primary outcomes investigated in this study were mean birthweight, low birthweight (LBW), and small-for-gestational age (SGA). A multivariable linear regression analysis was performed to explore the association between changes in EMT following progesterone administration and newborns' birthweight.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eDespite any fluctuations in EMT levels on the day of FET compared to one day prior to progesterone administration, there were no statistically significant differences observed in the absolute mean birthweight of singletons among the three groups (3355.30\u0026thinsp;\u0026plusmn;\u0026thinsp;502.69 vs. 3351.30\u0026thinsp;\u0026plusmn;\u0026thinsp;474.79 vs. 3344.26\u0026thinsp;\u0026plusmn;\u0026thinsp;514.54, P\u0026thinsp;=\u0026thinsp;0.753). In comparison to the stable EMT group, the decreased EMT group had incidences of LBW and SGA in term infants at 1.1% (adjusted odds ratio [aOR]: 1.645, 95% confidence interval [CI]: 0.818\u0026ndash;3.307) and 2.7% (aOR: 1.141, 95% CI:0.783\u0026ndash;1.662), respectively; however, there was no significant association between the increased EMT group and risks of LBW (aOR: 1.310, 95% CI:0.723\u0026ndash;2.375) or SGA (aOR:0.912, 95% CI:0.660\u0026ndash;1.261). The multiple linear regression analysis revealed that both gestational age and infant gender exerted significant influences on singleton birthweight, while any alteration in endometrial thickness subsequent to progesterone administration did not yield a statistically significant impact on singleton birthweight.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe extent of EMT may exhibit variability, either increasing, decreasing, or remaining stable on the day of frozen embryo transfer (FET) compared to one day prior to progesterone administration. However, it is important to note that changes in EMT following progesterone administration do not demonstrate an independent association with adverse perinatal outcomes in term infants during FET cycles.\u003c/p\u003e","manuscriptTitle":"Impact of endometrial thickness alteration in response to progesterone administration on neonatal outcomes in frozen embryo transfer cycles: analysis of 6331 singleton newborns","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-30 06:30:04","doi":"10.21203/rs.3.rs-5278874/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-21T17:23:52+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-19T05:36:45+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-10-19T05:35:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2024-10-17T01:30:39+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":"9897d06c-2357-40b9-b40e-b0dc3042fd6f","owner":[],"postedDate":"October 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-29T05:55:19+00:00","versionOfRecord":[],"versionCreatedAt":"2024-10-30 06:30:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5278874","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5278874","identity":"rs-5278874","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}