Variability of per- and polyfluoroalkyl substances concentrations among pregnant African American women and newborns

Background: Longitudinal trends in PFAS levels across pregnancy have not been thoroughly examined, despite emerging evidence linking prenatal PFAS exposures with adverse birth outcomes. We sought to characterize variability of longitudinal PFAS concentrations during pregnancy and to examine maternal-fetal transfer rate of PFAS among African Americans (AA). Method: We quantified serum concentrations of four PFAS in 376 participants and additional eight PFAS in 301 participants during early (8-14 weeks) and late (24-30 weeks) gestation, as well as levels of four PFAS in dried blood spots (DBS) from 199 paired newborns in the Atlanta AA Maternal-Child cohort (2014-2018). We characterized the variability of PFAS levels across gestation using intraclass correlation coefficients (ICC) and transfer rate. Multivariable linear regression models were fit to assess how maternal early or late serum PFAS concentrations predict newborn DBS PFAS levels. Results: Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected in >95% of both maternal and newborn samples, with PFHxS and PFOS having the highest median concentrations. All PFAS median concentrations increased across pregnancy, except for PFOA and N-methyl perfluorooctane sulfonamido acetic acid (NMFOSAA), which decreased. Prenatal PFAS were weakly to moderately correlated with newborn PFAS (-0.11< r < 0.54). Compared to late pregnancy, maternal PFAS in early pregnancy can better predict newborn PFAS while adjusting for covariates. We observed high variability in PFAS levels across pregnancy (ICC: 0.001-0.59), with the greatest change in PFHxS (ICC=0.001). The mean maternal-fetal transfer rate of PFAS decreased with increasing carbon chain length. Conclusions: In AA mother-newborn dyads, we found most PFAS concentrations increased across pregnancy, and the magnitude of variability differed by PFAS species. Future studies are needed to understand the within-person variability of PFAS during and after pregnancy in relation to birth outcomes. Keywords: PFAS; pregnancy; variability; transfer rate.