Prenatal Bisphenol A Urine Concentrations and Early Rapid Growth and Overweight Risk in the First Years of Life

Abstract

Background: Increasing experimental evidence suggests that developmental exposure to bisphenol A (BPA) increases offspring weight gain later in life. However, this hypothesis has not yet been explored in prospective cohort studies. Aim: We examined the effects of maternal BPA exposure during pregnancy on rapid growth in the first 6 months of life and subsequent body mass index (BMI) and waist circumference at the ages of 14 months and 4 years. Methods: BPA concentrations were measured in two spot urine samples collected in the 1st and 3rd trimesters of pregnancy from mothers of the Spanish INMA birth cohort study (N=402). The average of the two creatinine-adjusted BPA concentrations was used as exposure variable. Rapid growth was defined as a weight gain z-score > 0.67 in the first 6 months of life. Child age-and-sex specific BMI z-scores were calculated at age 14 months and 4 years based on the WHO referent; overweight was defined as a BMI z-score ? the 85th percentile. Age-and-sex-specific waist circumference z-scores were calculated at age 14 months and 4 years using the analysis population mean. Results: Twenty-six percent of infants were rapid growers, 26% were overweight at 14 months and 21% at 4 years. BPA concentrations (GM±GSD) were 2.6 ± 2.3 in 1st and 2.0 ± 2.3 ?g/g creatinine in 3rd trimester samples (Pearson r=0.13, p<0.01). At 4 years, associations were observed between BPA exposure and increased waist circumference (? z-score per log10 ?g/g: 0.29; 95% CI: 0.01, 0.58) and BMI (? z-score: 0.27; 95%CI: -0.08, 0.62). BPA was not related to the obesity-related outcomes assessed at earlier ages. Conclusions: Findings suggest an association between BPA exposure and obesity-related outcomes in childhood, but not earlier in infancy. The short half-life and large within-person variability of BPA exposure create uncertainties in exposure assessment which may have biased results towards the null hypothesis.