Risk factors for neonatal admission from the beginning of pregnancy in Northeast Spain.

Data update: This study presents updated demographic and obstetric data, with a consistent sample size of newborns over five years in a Mediterranean region (northern Spain). Confirmation of specific risk factors: The study highlights that nulliparity, the use of fertility techniques, and multiple pregnancies are key risk factors for neonatal admission and prematurity. Contextualization of the migratory impact: The study identifies that newborns of foreign mothers are at greater risk of admission and prematurity, mainly due to social and cultural factors, emphasizing the importance of integration policies in prenatal care. Data update: This study presents updated demographic and obstetric data, with a consistent sample size of newborns over five years in a Mediterranean region (northern Spain). Confirmation of specific risk factors: The study highlights that nulliparity, the use of fertility techniques, and multiple pregnancies are key risk factors for neonatal admission and prematurity. Contextualization of the migratory impact: The study identifies that newborns of foreign mothers are at greater risk of admission and prematurity, mainly due to social and cultural factors, emphasizing the importance of integration policies in prenatal care.

Data were collected between February 2017 and February 2022, comprising information on 9722 newborns. After filtering based on gestational age and need for admission, the final sample consisted of 9560 newborns (Fig.  1 ). Flow chart showing the study population. a Term newborn not admitted, b term newborn admitted, c newborn 33–36 gestacional age, d newborn ≤32 gestacional age. Table  1 displays the analysis of demographic and obstetric factors at the onset of pregnancy associated with neonatal admission risk at our hospital across the previously mentioned subgroups. The table indicates that maternal smoking during pregnancy is not a risk factor for newborn admission or premature delivery. The remaining factors under investigation show statistically significant results in at least two of the three groups of admitted newborns compared to those not admitted, except for housing in rural areas, which is only significant in the admitted premature newborns group aged 33–36 weeks (OR 1.32; 95% CI: 1.06–1.65) (Table  1 ). Among the analysed factors, nulliparity, the need for fertilisation, and multiple gestation techniques stood out quantitatively (OR: 22.48, 4.04 and 3.34, respectively), emerging as significant risk factors for newborn admission at term and premature delivery. The risk associated with these variables for prematurity increases in the younger gestational age group (Table  1 ). Regarding maternal origin, infants born to foreign‐born mothers exhibit a higher risk of admission in the full‐term NB group (OR 1.26; 95% CI: 1.10–1.43) and in premature births <32 weeks (OR 1.61; 95% CI: 1.09–2.38). Demographic and obstetric factors at the start of pregnancy associated with the risk of neonatal admission in our hospital, 2017–2022 95% confidence interval for the odds ratio compared to the healthy newborn group. Results with p<0.05 were considered statistically significant. P : differences compared to the healthy newborn group. GA, gestational age in weeks; NB, newborn. Table  2 presents the results of the Stepwise Backward analysis. The chi‐square of the likelihood ratio (Omnibus) demonstrates statistical significance ( P  < 0.001) across the three analysed groups. The correlation coefficient of the analysed model (Nagelkerke R2) ranges from R2: 0.174 to R2: 0.265 depending on the gestational age of the admitted newborns. The predicted value (correct percentage) of the model exceeded 90% in all three analysed groups, with the highest percentage (98.8%) observed in the premature newborn group <32 weeks of gestational age. Regarding the OR of this model, the variable that contributes the most risk quantitatively for admission in the three studied groups is nulliparity compared to multiparity. Second, multiple gestation, particularly concerning premature birth, followed by the need for fertilisation techniques and the foreign origin of the mother, all represent significant risks in all the studied groups (Table  2 ). The model has excluded variables of maternal age >35 years and rural origin in both groups of admitted premature newborns. Stepwise backward model (logistic regression) for demographic and obstetric factors at the start of pregnancy associated with the risk of neonatal admission 95% confidence interval for the odds ratio compared to the healthy newborn group. Results with p<0.05 were considered statistically significant. Hyphen (‐) denotes values eliminated or excluded due to non‐significant statistical test results ( P  < 0.05). GA, gestational age in weeks; NB, newborn.

Ensuring maternal well‐being and effective gestational oversight are vital for averting potential complications during pregnancy and, consequently, are fundamental factors influencing neonatal health. 1 An illustration of this can be found in the prenatal care approach advocated by the WHO, which advocates increasing the number of prenatal visits for pregnant women from four to eight. Recent studies suggest that a higher frequency of prenatal consultations in women and adolescents correlates with a reduced likelihood of prenatal deaths. Engaging in prenatal care with a minimum of eight consultations can diminish perinatal mortality rates by up to 8 per 1000 births, in contrast to a minimum of four visits. 2 This approach not only enhances maternal and fetal evaluations but also fosters improved communication with healthcare providers, thereby enhancing the likelihood of optimal pregnancy outcomes. 2 , 3 Factors such as tobacco use during pregnancy, maternal age, the use of in vitro fertilisation procedures, prior pregnancies, or multiple pregnancies have been described in the scientific literature as possible risk factors for neonatal health. 4 , 5 , 6 , 7 , 8 , 9 , 10 The presence and coexistence of these factors during pregnancy can be influenced by socio‐economic and cultural aspects, resulting in varying proportions depending on the characteristics of the population group. Understanding, studying, and detecting these factors are essential for proper obstetric management, starting with prevention campaigns and continuing with close gestational and neonatal monitoring. 3 The aim of this paper is to describe and analyse specific demographic and obstetric variables present at the onset of pregnancy, which are associated with the risk of neonatal admission (newborns admitted to a neonatal intensive care unit), in our healthcare area over a 5‐year period (2017–2022) and to assess their actual impact.

The present study investigates the influence of diverse demographic and obstetric factors at the onset of pregnancy on the risk of neonatal admission and prematurity in a northern region of Spain over a 5‐year period (2017–2022). A representative sample of the study groups was selected, ensuring an adequate sample size for each group. Neonatal health stands as a cornerstone in ensuring the optimal development of infants, laying the foundation for their growth and overall well‐being. The care and attention provided during this pivotal phase not only impact the immediate survival of the newborn but also exert a lasting influence on their long‐term quality of life. Recognising, identifying, and effectively addressing risk factors during pregnancy are essential pillars for enhancing perinatal health. In our study, nulliparity has emerged as the main risk factor for admission in the neonatal period, as well as for prematurity, only surpassed by multiple gestation in the group of premature NB of 33–36 SEG. The absence of previous children has already been described in the scientific literature as a risk factor for low birth weight and neonatal mortality. 10 , 11 A higher incidence of caesarean section, postpartum bleeding, and neonatal resuscitation has also been reported. 12 These results have been related to several factors. On the one hand, a lower level of health knowledge has been proposed in this population group, which would justify a more deficient gestational control. 13 On the other hand, it has been suggested that women with a higher risk during gestation may not have had subsequent live births, either by choice or due to differences in fertility. 14 The prevalence of spontaneous twin pregnancy is approximately 1%–2%. However, in recent decades, particularly in developed countries, it has risen to 3%–4%, primarily attributed to elective delay in maternity and the growing utilisation of assisted reproduction techniques. 15 , 16 Twin pregnancies are linked with an elevated risk of caesarean section, preterm birth, intrauterine growth restriction (IUGR), bronchopulmonary dysplasia, and perinatal mortality, among other complications. 15 , 16 , 17 , 18 Our findings are in line with existing literature, reaffirming the heightened risk of neonatal admission among full‐term twin newborns (OR 2.4; 95% CI: 1.39–4.16), which escalates significantly within the premature groups, both 33–36 weeks of gestation and <32 weeks of gestation (OR 17.67 and 13.76, respectively). Newborns conceived through fertilisation techniques are subjected to maternal conditions associated with underlying infertility, such as ovulatory disorders, tubal disorders, and endometriosis, as well as the fertilisation process itself. Consequently, adverse outcomes are observed among these newborns, including prematurity, low birth weight, and macrosomia, among other complications. 19 , 20 , 21 Our study confirms the influence of fertilisation techniques on prematurity and neonatal health. However, a significant decrease in its impact as a risk factor (decrease in OR) is observed after the stepwise backward analysis. This reduction in impact can be attributed to the existence of cofactors such as maternal age, nulliparity, and multiple gestation, all closely associated with fertilisation techniques and re‐evaluated in the model to ascertain the individual contribution of each variable. The health status of immigrant populations has been extensively studied in the scientific literature. In countries such as Canada, the United States, and Australia, the phenomenon known as ‘healthy immigration’ has been identified, wherein immigrant populations exhibit better health outcomes compared to native populations. 22 , 23 , 24 , 25 While population migrations have been a constant in human societies, their health implications have garnered increased attention from the WHO European Region since the mid‐2000s. As of 2017, the European region was home to over 90 million migrants, comprising nearly 10% of the total population and 35% of international migrants worldwide. 26 In our population, first‐generation migrants are at risk of social exclusion. Our study unveils noteworthy findings concerning newborns based on maternal origin, revealing an elevated risk of neonatal unit admission among infants born to mothers of foreign origin, as well as premature births <32 weeks of gestation. These outcomes likely stem from socio‐cultural and economic factors that contribute to inadequate gestational care and heightened perinatal morbidity. 27 It is worth noting that individuals of foreign origin encounter obstacles in accessing healthcare services, including unfamiliarity with the healthcare system, lack of social resources, and language barriers, among other challenges. 28 , 29 , 30 , 31 , 32 Nevertheless, it has been observed that residing in countries with policies aimed at integrating immigrant populations, such as the universal healthcare system in Spain and other European Union countries, serves as a protective factor against the socio‐cultural barriers previously described. This integration acts as a mitigating factor for obstetric and perinatal complications stemming from these barriers. 26 , 32 The maternal age at gestation in Europe has progressively increased since the 1970s. 33 The age threshold at which maternal age is considered a risk factor for the newborn remains a topic of debate. However, several studies have proposed >35 years as a valid cut‐off point. 33 , 34 , 35 , 36 Advanced maternal age has been associated with lower birth weight and higher rates of prematurity, likely due to increased complications during pregnancy and prolonged labour. 33 , 35 , 36 In our study, maternal age >35 years has been shown to be a risk factor for neonatal admission of full‐term newborns, but this was not observed in premature newborns according to the statistical model. This may be due to the interplay of several factors associated with maternal age, such as IVF, multiple gestation resulting from fertility treatments, or nulliparity. These factors are significant determinants of neonatal morbidity and prematurity. Housing in rural areas has been excluded by the model in our sample for both groups of preterm admitted newborns. However, it has been considered a weak protective factor for the group of full‐term admitted newborns. This finding can be explained by the demographic characteristics of our population. The rural areas served by our hospital are mostly easily accessible for patients, with short travel times. This results in minimal impact on the quality of prenatal care, and consequently, on neonatal health. Finally, although tobacco use during pregnancy has been widely described in the scientific literature as a gestational risk factor, 37 , 38 , 39 , 40 our study did not identify it as a risk factor for neonatal admission or prematurity. This discrepancy may be due to the limitations of our study, such as not quantifying the number of cigarettes consumed. The relationship between tobacco consumption and its negative effects on pregnancy is directly proportional; consuming more than 20 cigarettes per day has been identified as a clear risk factor, while lower consumption may have a lesser impact. 37 Therefore, given the lack of statistical significance in our study regarding this well‐known risk factor, the most plausible explanation is that moderate to low tobacco consumption has a reduced impact on neonatal health.

In our study, among the demographic and obstetric variables at the beginning of pregnancy associated with the risk of neonatal admission and premature delivery, nulliparity emerges as the primary risk factor for both outcomes, followed by multiple gestation in premature newborns. Additionally, the utilisation of fertilisation techniques and maternal foreign origin significantly elevate the risk of admission and neonatal prematurity in our sample. Recognising one or more of these risk factors underscores the importance of considering them early in gestational follow‐up. Furthermore, the influence of advanced maternal age on neonatal admission likely stems from the combined effect of several of the aforementioned factors. These findings underscore the necessity of implementing a comprehensive approach to prenatal care. By doing so, we can not only enhance neonatal prognosis but also promote long‐term health outcomes.

The limitations of the study include population differences which, although mitigated by the sample size, must be considered when extrapolating the data to other populations. Another limitation is the incomplete documentation of certain data, such as family socioeconomic status or the number of cigarettes smoked per day, which could either overestimate or underestimate the impact of the risk factors studied. These gaps in the data highlight the need for cautious interpretation of the results and suggest areas for improvement in future research.

This study was designed following the guidelines of the STROBE (Strengthening the Reporting of Observational studies in Epidemiology) initiative for observational studies. This retrospective study was conducted in a tertiary hospital in Northeast Spain using the database used in our hospital to record data and postnatal progress of all newborns while in hospital, whether or not they were admitted. The inclusion criteria for this study included patients born between February 2017 and February 2022, obtaining an initial sample of 9722 newborns. Additionally, the database used had to contain information on gestational age and whether or not the patients required admission during the immediate postnatal period. Another inclusion criterion was that all relevant data for the study had to be recorded in the database prior to analysis. The study sample included variables such as nulliparity or multiparity, single or multiple gestation, method of fertilisation (assisted reproductive techniques or natural conception), maternal origin (Spanish or foreign‐born), maternal age (less than or equal to and greater than 35 years), and the family home located in the urban nucleus or in rural area. In this study we have considered as foreign maternal origin those mothers born outside of Spain (first generation migrants). To avoid bias, we ensured that each of the groups analysed had a sufficiently representative sample of our population. Additionally, the data were matched based on the need for admission and gestational age at birth. By maintaining a balanced representation, we aimed to enhance the validity and generalizability of our findings. The total sample has been divided into two groups based on the need for newborn (NB) admission. The group of healthy NB consists of infants born at term who did not require admission during their postnatal stay, while the admitted NB were those who required admission to the neonatal unit. Within the admitted group, NB were further classified into the following subgroups based on their gestational age at birth: (i) NB born at or before 32 weeks of gestational age; (ii) NB born between 33 and 36 weeks of gestation; (iii) NB born at term. To conduct the statistical analysis, SPSS (Statistical Package for Social Sciences) version 25.0 was utilised. A descriptive analysis was performed, presenting qualitative variables using percentage distributions for each category. Subsequently, the odds ratio (OR) was calculated for different proportions along with their confidence intervals (95% CI) concerning the healthy newborn group. A Stepwise Backward analysis was employed to select relevant independent variables for inclusion in a logistic regression model across the three groups of admitted newborns based on their gestational age. This process employs logistic regression to select the most relevant variables for the model, simplifying it by retaining only those variables that have a significant impact on the response variable and eliminating those that do not. The variable of tobacco consumption during pregnancy was excluded from the outset due to a lack of statistical significance. Results with P  < 0.05 were considered statistically significant.