Maternal body mass index and the risk of short-term neurological outcomes: a nationwide Korean cohort

Objectives Maternal obesity is a well-known factor influencing pregnancy outcomes. However, the influence of maternal obesity on neonatal neurological morbidities, such as intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and retinopathy of prematurity (ROP), remains unclear. We aimed to evaluate the association between maternal body mass index (BMI) and short-term neonatal neurological morbidities using a nationwide cohort.Methods Using the Korean National Health Information Database, we conducted a retrospective cohort study with data obtained between 2014 and 2021. Maternal BMI was categorized on the basis of the Asia-Pacific classification: underweight (< 18.5 kg/m2), normal weight (18.5–22.9 kg/m2), overweight (23.0–24.9 kg/m2), obese class I (25.0–29.9 kg/m2), and obese class II or higher (≥ 30.0 kg/m2). Neonatal outcomes (IVH, PVL, and ROP) were identified using ICD-10 codes. Inverse probability of treatment weighting was used to adjust for potential confounders. The relative risks (RRs) for each outcome were estimated using robust Poisson regression.Results Among 779,091 neonates, a dose-dependent increase in risk was observed across higher BMI categories. Maternal obesity (BMI ≥ 30.0 kg/m2) was associated with significantly higher risks of IVH (RR, 3.19; 95% confidence interval [CI], 3.02–3.36), PVL (RR, 3.02; 95% CI, 2.75–3.32), and ROP (RR, 3.66; 95% CI, 3.37–3.98) in comparison with normal BMI. Conversely, maternal underweight (BMI < 18.5 kg/m2) was associated with reduced risk of IVH (RR, 0.86; 95% CI, 0.81–0.92), PVL (RR, 0.86; 95% CI, 0.76–0.96), and ROP (RR, 0.73; 95% CI, 0.65–0.82).Conclusions Maternal obesity was associated with an increased risk of neonatal neurological morbidities, including IVH, PVL, and ROP, with a dose-dependent association. These findings emphasize the importance of optimizing maternal BMI before pregnancy to reduce the risk of neurological complications in neonates and demonstrate the need for public health policies focused on maternal weight management.