The effect of body mass index on maternal and neonatal health in term pregnancies: a cross-sectional study in Turkey

Backgroud and objective: Maternal obesity and gestational weight gain (GWG) are important determinants of maternal and neonatal health outcomes. This study aimed to investigate the effects of prepregnancy body mass index (PPBMI) and GWG on maternal and neonatal outcomes in Türkiye. Methods: This prospective cross-sectional study was conducted in a public hospital in Turkey between December 2021 and December 2022. A total of 1137 women between the ages of 19 and 45 who had singleton and live births and had complete medical records were included in the study using simple random sampling. Data were collected using medical records and a structured interview form. PPBMI and GWG were calculated from self-reported weight and height data. Kruskal-Wallis, Mann-Whitney U, and binary logistic regression tests were used to analyze the data. Results: Among the participants, 4.7% were underweight, 61% had a normal weight, 27.6% were overweight, and 9.9% were obese on the basis of PPBMI. According to the Institute of Medicine (IOM) GWG guidelines, 17.2% had insufficient GWG, 55.1% had adequate GWG, and 27.8% had excessive GWG. Overweight women had significantly increased odds of gestational diabetes mellitus (OR = 0.479, p = 0.024), genital tract infections (OR = 2.15, p = 0.000), urinary tract infections (OR = 2.42; p = 0.011), elective cesarean delivery (OR = 8.62, p = 0.035), macrosomia (OR = 9.15, p = 0.031), and low APGAR (Appearance, Pulse, Grimace, Activity, Respiration) scores (< 7 at 5 min) (OR = 0.20, p = 0.000). Obese women also showed higher odds of elective cesarean (OR = 9.56; p = 0.030) and macrosomia (OR = 8.27, p = 0.044). Underweight women had higher odds of neonatal hospital stay > 5 days. Insufficient GWG was associated with increased risks of low birth weight (OR = 0.46, p = 0.013), third-trimester bleeding (OR = 0.45, p = 0.016), and neonatal hospitalization > 5 days (OR = 0.44, p = 0.003), while macrosomia risk was lower (OR = 2.06, p = 0.001). Conclusion: PPBMI and GWG are significant predictors of maternal and neonatal health outcomes. Elevated PPBMI and inappropriate GWG are associated with increased risks of gestational diabetes, macrosomia, cesarean delivery, low APGAR scores, low birth weight, and prolonged neonatal hospitalization. These findings highlight the critical role of routine assessment and management of maternal weight status and weight gain during prenatal care in reducing preventable complications for both mothers and their newborns. © The Author(s) 2025.