Exposure to Endocrine-Disrupting Chemicals During Pregnancy Is Associated with Weight Change Through 1 Year Postpartum Among Women in the Early-Life Exposure in Mexico to Environmental Toxicants Project

Background: The postpartum period may be a vulnerable life stage for a woman's cardiometabolic health. We examined associations of exposure to common endocrine-disrupting chemicals (EDCs) during pregnancy with weight from delivery through 1 year postpartum among 199 women in Mexico City. Materials and Methods: During each trimester of pregnancy, we collected a urine sample to assay bisphenol A (BPA), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), mono-3-carboxypropyl phthalate (MCPP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and monoethyl phthalate (MEP). We calculated summary scores for di-2-ethylhexyl phthalate metabolites (sigma DEHP) and dibutyl phthalate metabolites (sigma DBP). We calculated the geometric mean of each EDC across pregnancy for use in the analysis. At delivery and three additional times during the first year postpartum, we measured the women's weight. We used mixed-effects linear regression models to estimate associations of each EDC with weight at delivery (kg) and weight change (kg/year) from delivery through 1 year postpartum. Covariates included urinary specific gravity, maternal age, parity, height, first trimester body mass index, and gestational age at enrollment. Results: Mean +/- standard deviation weight change during the first postpartum year was -0.49 +/- 4.04 kg. The EDCs were inversely associated with weight at delivery, but positively associated with weight change through 1 year postpartum. For example, each interquartile range of urinary sigma DEHP corresponded with 1.38 (95% confidence interval: 0.44-2.33) kg lower weight at delivery and 1.01 (0.41--1.61) kg/year slower rate of weight loss. We observed similar associations for other EDCs. Conclusions: Prenatal exposure to EDCs is associated with lower weight at delivery, but slower rate of weight loss through the first postpartum year.