Prepregnancy BMI Modified the Association Between Gestational Weight Gain and Birth Weight in Preterm Neonates

Maternal prepregnancy body mass index (BMI), gestational weight gain (GWG), and physical activity during pregnancy are associated with neonatal birth weight. This study aimed to evaluate their associations and interactions specifically among preterm neonates. Both inadequate and excessive GWG were associated with an increased risk of low birth weight (LBW) ( P < .05). Inadequate GWG was associated with an increased risk of LBW only in underweight and normal weight women, while excessive GWG was related to an increased risk of LBW only in overweight/obese women ( P = .001), indicating that maternal prepregnancy BMI may modify the association between GWG and preterm neonatal birth weight.