Early-Life Bisphenol A Exposure and Child Body Mass Index: A Prospective Cohort Study

BACKGROUND: Early-life exposure to bisphenol A (BPA) may increase childhood obesity risk, but few prospective epidemiological studies have investigated this relationship. OBJECTIVE: We sought to determine whether early-life exposure to BPA was associated with increased body mass index (BMI) at 2-5 years of age in 297 mother-child pairs from Cincinnati, Ohio (HOME Study). METHODS: Urinary BPA concentrations were measured in samples collected from pregnant women during the second and third trimesters and their children at 1 and 2 years of age. BMI z-scores were calculated from weight/height measures conducted annually from 2 through 5 years of age. We used linear mixed models to estimate BMI differences or trajectories with increasing creatinine-normalized BPA concentrations. RESULTS: After confounder adjustment, each 10-fold increase in prenatal (beta = -0.1; 95% CI: -0.5, 0.3) or early-childhood (beta = -0.2; 95% CI: -0.6, 0.1) BPA concentrations was associated with a modest and nonsignificant reduction in child BMI. These inverse associations were suggestively stronger in girls than in boys [prenatal effect measure modification (EMM) p-value = 0.30, early-childhood EMM p-value = 0.05], but sex-specific associations were imprecise. Children in the highest early-childhood BPA tercile had lower BMI at 2 years (difference = -0.3; 95% CI: -0.6, 0.0) and larger increases in their BMI slope from 2 through 5 years (BMI increase per year = 0.12; 95% CI: 0.07, 0.18) than children in the lowest tercile (BMI increase per year = 0.07; 95% CI: 0.01, 0.13). All associations were attenuated without creatinine normalization. CONCLUSIONS: Prenatal and early-childhood BPA exposures were not associated with increased BMI at 2-5 years of age, but higher early-childhood BPA exposures were associated with accelerated growth during this period.