Association between PFAS and renal function indicators in cord blood of newborns: modifying effects of newborn sex and maternal factors

BACKGROUND: Evidence on the associations between per- and polyfluoroalkyl substances (PFAS) exposure and renal function in newborns remains limited, particularly in cord blood studies. This retrospective cross-sectional study aimed to explore the associations between individual and mixed PFAS exposure with renal function indicators in the cord blood and to examine whether these associations were modified by newborn sex and maternal factors. MATERIALS AND METHODS: A total of 403 newborns with available cord blood samples were included. Six PFAS and renal function indicators were measured in cord blood. Multivariable linear regression, quantile-based g-computation (qgcomp), and Bayesian kernel machine regression (BKMR) models were used to evaluate the associations of individual and mixed PFAS exposure with blood urea nitrogen (BUN), creatinine (Cr), the BUN-to-Cr ratio (UCR), and estimated glomerular filtration rate (eGFR). RESULTS: In multivariable linear regression analyses, perfluorobutanoic acid (PFBA) and perfluorononanoic acid (PFNA) were positively associated with BUN; PFBA, perfluorooctanoic acid (PFOA), and PFNA were positively associated with the UCR; and PFBA and perfluorohexanoic acid (PFHxA) were positively associated with eGFR. PFBA and PFHxA were inversely associated with Cr. Mixture analyses further showed that PFAS co-exposure was positively associated with BUN, UCR, and eGFR, but negatively associated with Cr. These associations were more pronounced among male newborns, those delivered vaginally, and those born to mothers aged ≤30 years with a normal pre-pregnancy body mass index. CONCLUSION: These findings suggest that prenatal co-exposure to PFAS, particularly PFBA, PFNA, PFOA, and PFHxA, may be associated with alterations in renal function indicators in newborns. The associations appeared to differ by newborn sex and maternal characteristics. Prospective longitudinal studies are needed to determine whether these early biomarker differences persist after birth and are related to later kidney outcomes.