Profiles and maternal-to-fetal transfer of per- and polyfluoroalkyl substances in paired maternal-infant biological matrices: A birth cohort study in Chengdu, China.

Per- and polyfluoroalkyl substances (PFAS) have been associated with adverse maternal and developmental health outcomes. However, studies on PFAS profile in multiple matched mother-infant samples remain limited. In this study, we aimed to characterize exposure levels and maternal-to-fetal transfer patterns of both conventional and emerging PFAS in a birth cohort from Chengdu, China. Concentrations of 24 PFAS were quantitatively determined in 47 pairs of maternal and infant samples, including maternal serum, cord serum, amniotic fluid, maternal urine, infant urine, and breast milk, using high-performance liquid chromatography-tandem mass spectrometry. The concentration ratios of PFAS in cord serum, amniotic fluid, and breast milk to maternal serum were calculated to assess their distribution across maternal, fetal, and neonatal matrices. The results indicated that both pregnant women and their offsprings were extensively exposed to PFAS. Emerging PFAS, including 6:2 chlorinated perfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA), 6:2 fluorotelomer sulfonic acid, and sodium p-perfluorous nonenoxybenzene sulfonate (OBS), were generally detected in maternal serum, cord serum, and amniotic fluid. Perfluoroundecanoic acid (PFUnDA) was the predominant PFAS in maternal and cord serum, whereas the emerging compound OBS was the dominant PFAS in amniotic fluid. Perfluorooctanoic acid (PFOA), PFUnDA, and 6:2 Cl-PFESA in cord serum and amniotic fluid showed significant positive correlations with maternal serum levels (p < 0.05). Notably, emerging PFAS, particularly OBS, exhibited significantly higher transplacental transfer efficiencies (as indicated by cord-maternal concentration ratios) compared to legacy PFAS, such as PFOA and PFUnDA, OBS also had the highest accumulation in amniotic fluid. These findings highlight a potentially greater fetal exposure risk to these emerging contaminants, providing critical data for understanding PFAS exposure characteristics and informing public health policies aimed at protecting maternal and child health in China.