Prepregnancy overweight and obesity and the risk of adverse pregnancy outcomes

The rising worldwide rates of overweight and obesity make it more probable that an increasing number of women with elevated body mass index (BMI) are conceiving. Therefore, it is crucial to recognize the negative pregnancy outcomes associated with BMI. This retrospective cohort study examined data from mothers who delivered at a tertiary medical facility in Iran, from January 2022 to January 2023. 2930 mothers were categorized into three groups: (1) Normal weight (BMI: 18.5-24.9 kg/m2); (2) Overweight (BMI: 25.0-29.9 kg/m2); and (3) Obese (BMI ≥ 30.0 kg/m2). The outcome measures consisted of maternal or neonatal complications. Binomial logistic regression models were utilized to determine ORs. The prevalence of overweight and obesity among our population was 27.9% and 6.5% respectively. The instances of normal vaginal delivery were significantly lower in overweight mothers than in those of normal weight. As the overweight score increased, the odds of preeclampsia and gestational diabetes increased by 2.148 and 1.319, respectively, while normal vaginal delivery experienced a decrease of 0.583. The likelihood of induced labor, preeclampsia, gestational diabetes, vaginal delivery, and maternal intensive care unit (ICU) admission was significantly different in obese mothers compared to those with normal weight. With each increase in the obesity score, the odds of induced labor, preeclampsia, gestational diabetes, and maternal ICU admission increased by 2.046, 3.079, 2.378, and 5.088 respectively. As the obesity score increased, the chances of a normal vaginal delivery decreased by 0.438. Overweight or obese mothers face the risks of preeclampsia, gestational diabetes, labor induction, maternal ICU admission, and a reduced rate of normal vaginal deliveries. The likelihood of these conditions increases with a higher body mass index.