Association between gestational urinary bisphenol a concentrations and adiposity in young children: The MIREC study

Background: Bisphenol A (BPA) is a high production volume chemical and because of its use in many consumer products, exposure is ubiquitous. Gestational BPA exposure has been associated with excess adiposity in rodent studies, but not consistently in human studies. We investigated the relation between gestational BPA exposure and early childhood adiposity in a prospective cohort study of 719 mother-child pairs. Methods: We used data from the MIREC Study, a prospective Pan-Canadian pregnancy and birth cohort study. We measured BPA in urine samples collected at an average of 12.1 weeks (range: 6.3–15 weeks) gestation and measured children's weight, height, waist/hip circumference, and subscapular/triceps skinfold thickness at an average age of 3.5 years (range: 1.9–6.2). We estimated covariate-adjusted associations of log₂-transformed BPA concentrations with child adiposity measures and examined whether these associations differed in boys and girls. Results: Median BPA concentrations were 0.8 ng/mL (IQR: 0.5–1.4). Among both boys and girls, each 2-fold increase in BPA concentrations was associated with higher waist-to-hip ratio (β: 0.003; 95% CI: 0.001, 0.005). The association of BPA with waist circumference and subscapular skinfold thickness was modified by sex (sex x BPA interaction p-values<0.2). In girls, each 2-fold increase in BPA concentrations was associated with a 0.2 cm (95% CI: 0.0, 0.5) and 0.15 mm (95% CI: 0.01, 0.30) increase in waist circumference and subscapular skinfolds, respectively. Associations were generally null or slightly inverse in boys. Conclusions: In this cohort, gestational urinary BPA concentrations were associated with subtle increases in girl's central adiposity during early childhood.