Prenatal exposure to phthalates and childhood body size in an urban cohort

Background: Phthalate exposures are hypothesized to increase obesity; however, prior research has been largely cross-sectional. Objective: We evaluated associations between prenatal phthalate exposures and body mass index (BMI) at child ages 5 and 7 years. Methods: Nine metabolites of six phthalates—di(2-ethylhexyl) phthalate (DEHP), di-n-octyl-, di-iso-butyl-, di-n-butyl-, butylbenzyl-, and diethyl phthalates—were measured in spot urine samples collected from pregnant African-American and Dominican women during their third trimester, and from their children at ages 3 and 5 years. To reduce multiple comparison issues, we initially used principal component analysis (PCA) to identify major patterns of natural log (ln)-transformed metabolite concentrations. Height and weight were assessed at ages 5 and 7 years, and fat mass and waist circumference at age 7. Linearized generalized estimating equation analyses related maternal component scores to child anthropometric outcomes at ages 5 (n = 326) and 7 (n = 330) years. Results: PCA identified a DEHP component and a non-DEHP component. In boys, higher maternal non-DEHP, but not DEHP, component scores were associated with lower BMI z-score (β = –0.30; 95% CI: –0.50, –0.10, n = 156), lower fat percentage (β = –1.62; 95% CI: –2.91, –0.34, n = 142), and smaller waist circumference (β = –2.02; 95% CI: –3.71, –0.32, n = 124). No significant associations with anthropometric outcomes were seen in girls (for BMI z-score, β = 0.07; 95% CI: –0.18, 0.31, n = 181). Interactions between sex and non-DEHP component association with outcomes were statistically significant (p < 0.01). Conclusions: Contrary to hypotheses, prenatal non-DEHP phthalate exposures were associated with lower BMI z-score, waist circumference, and fat mass in boys during early childhood.