Exposure to Legacy and Novel Per- and Polyfluoroalkyl Substances and Diminished Ovarian Reserve: Evidence from Blood-Follicle Transfer and Mixture Risk Assessment in Reproductive-Aged Women.

Emerging evidence implicates per- and polyfluoroalkyl substances (PFAS) in adverse alterations to the follicular microenvironment, yet their potential contribution to diminished ovarian reserve (DOR) remains poorly characterized. This study systematically quantified both legacy and novel PFAS in matched plasma and follicular fluid samples from reproductive-aged women in Shenyang, China (2017-2020), and determined compound-specific blood-follicle transfer efficiencies (BFTEs). A matched case-control design, controlling for age and body mass index (BMI), was applied to evaluate associations between PFAS concentrationsboth as individual analytes and as chemical mixturesin follicular fluid and the presence of DOR, as assessed by anti-Müllerian hormone (AMH) and antral follicle count (AFC). Two perfluoroalkyl ether carboxylic acids (PFECA) (PFMOAA and PFO5DoDA) were identified for the first time in human follicular fluid. BFTEs exhibited substantial variability (62.43%-470.93%) and a clear inverse relationship with carbon chain length, with short-chain perfluorocarboxylic acids (PFCA) (PFBA and PFHpA) and PFECA (PFMOAA and PFO5DoDA) showing marked preferential partitioning into follicular fluid (BFTE > 1). Elevated follicular concentrations of PFBA and PFPeA were significantly associated with increased DOR risk, accompanied by concomitant reductions in AMH and AFC. Mixture modeling further demonstrated a positive association between total PFAS burden and DOR. Bayesian kernel machine regression identified short-chain PFCA and PFECA as the principal contributors, with PFBA representing the dominant driver of the observed effect. These findings reveal the bioaccumulation of short-chain PFAS in follicles, including emerging compounds, and provide compelling evidence for their involvement in impaired ovarian function which has direct implications for reproductive risk assessment in women.