The joint and interactive effects of household income, delivery mode with prenatal BPA exposure on offspring early postnatal growth trajectories: A prospective cohort study.

This study aims to explore the association between prenatal bisphenol A (BPA) exposure and the offspring's BMI for age z-score (BAZ) trajectories from 0 to 3 months, and to analyze the potential influences of household income and delivery mode. In a prospective cohort of 997 mother-infant pairs, maternal urinary BPA was measured in late pregnancy, and infants were followed up at 1 and 3 months after birth. Mixed linear model showed that prenatal BPA exposure was negatively associated with average BAZ levels in offspring aged 0-3 months. Group-based trajectory model (GBTM) identified three BAZ trajectory patterns: low, moderate, and high growth. Although prenatal BPA exposure was not associated with BAZ trajectories in the overall population, subgroup analyses suggested heterogeneity by household income and delivery mode. BPA exposure was associated with an increased risk of low-growth trajectory in infants from low-income families. Moreover, BPA exposure increased high-growth trajectory risk in the vaginal delivery group but showed an opposite trend in the cesarean delivery group. A significant multiplicative interaction between BPA exposure and delivery mode was observed for the high-growth trajectory. These findings indicate that prenatal BPA exposure is negatively associated with overall BAZ levels during the early infancy, and its association with the risk of low/high BAZ trajectories varies by household income and delivery mode. Furthermore, BPA exposure takes joint and interactive effects with delivery mode on the BAZ trajectory; low BPA exposure and cesarean delivery could significantly increase the risk of a high-growth trajectory.