Midpregnancy Phthalate and Phenol Biomarkers in Relation to Infant Body Composition: The Healthy Start Prospective Cohort

BACKGROUND: Gestational phthalate and phenol exposure disrupts adipogenesis, contributing to obesity in mice. Whether gestational phthalate or phe-nol exposure is associated with infant body composition has not been investigated in humans.OBJECTIVE: We examined associations between biomarkers of phthalate and phenol exposure in midpregnancy and infant size and body composition at birth and at 5 months of age.METHODS: Analyses were conducted among 438 infants from the Healthy Start prospective pregnancy cohort. Sixteen phthalate and phenol bio-markers were quantified in spot urine samples collected at 24-28 wk of gestation. Infant outcomes measured at birth and at 5 months of age included size [weight (in grams)] and body composition [fat and lean masses (in grams); percentage fat mass]. Single-(linear) and multipollutant (quantile g-computation) models were used to estimate associations of phthalate and phenol biomarkers with infant outcomes at birth and at 5 months of age. Models were adjusted for sociodemographics, sample collection timing, and lifestyle factors and used to examine for effect modification by infant sex.RESULTS: In single-pollutant models, mono-benzyl phthalate and di -n-butyl phthalate were inversely associated with percentage fat mass [b: -0.49 (95% CI: -0.91, -0.08) and -0.51 (95% CI: -1.02, 0.01), respectively] in male but not female infants at birth. Similar, but less precise, associations were observed at 5 months of age. In multipollutant models, a 1-quartile increase in the phthalate and phenol biomarker mixture was inversely associ-ated with percentage fat mass at birth [-1.06 (95% CI: -2.21, 0.1)] and at 5 months of age [-2.14 (95% CI: -3.88, -0.39)] among males, but associ-ations were null among females [0.48 (95% CI: -0.78, 1.75) and -0.64 (95% CI: -2.68, 1.41), respectively]. Similar associations were observed with infant weight.CONCLUSION: In this U.S.-based prospective cohort, gestational phthalate and phenol biomarkers were inversely associated with infant weight and fat mass, particularly in males. https://doi.org/10.1289/EHP12500