Changes in Serum Concentrations of Maternal Poly- and Perfluoroalkyl Substances over the Course of Pregnancy and Predictors of Exposure in a Multiethnic Cohort of Cincinnati, Ohio Pregnant Women during 2003–2006

[Image: see text] Data on predictors of gestational exposure to poly- and perfluoroalkyl substances (PFASs) in the United States are limited. To fill in this gap, in a multiethnic cohort of Ohio pregnant women recruited in 2003–2006, we measured perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and six additional PFASs in maternal serum at ∼16 weeks gestation (N = 182) and delivery (N = 78), and in umbilical cord serum (N = 202). We used linear regression to examine associations between maternal serum PFASs concentrations and demographic, perinatal, and lifestyle factors. PFASs concentrations in maternal sera and in their infants’ cord sera were highly correlated (Spearman rank correlation coefficients = 0.73–0.95). In 71 maternal-infant dyads, unadjusted geometric mean (GM) concentrations (95% confidence interval) (in μg/L) in maternal serum at delivery of PFOS [8.50 (7.01–9.58)] and PFOA [3.43 (3.01–3.90)] were significantly lower than at 16 weeks gestation [11.57 (9.90–13.53], 4.91 (4.32–5.59), respectively], but higher than in infants’ cord serum [3.32 (2.84–3.89), 2.85 (2.51–3.24), respectively] (P < 0.001). Women who were parous, with a history of previous breastfeeding, black, or in the lowest income category had significantly lower PFOS and PFOA GM concentrations than other women. These data suggest transplacental transfer of PFASs during pregnancy and nursing for the first time in a U.S. birth cohort.