Abstract
BACKGROUND: An increasing body of evidence indicates that exposure to metal elements may adversely affect female fertility. While the association between metal concentrations in the follicular fluid (FF) and fertility is acknowledged, the relationship between metal exposure in FF and the outcomes of assisted reproductive technology (ART) remains ambiguous. METHODS: We quantified eight metals in FF from 139 reproductive-age women in China using a trace element analyzer. To assess their relationships with critical ART metrics, logistic regression, stratified analysis based on age and body mass index (BMI) were used. Additionally, restricted cubic splines (RCS) were applied to examine potential nonlinear relationships between metal concentrations and outcomes, and Bayesian kernel machine regression (BKMR) was employed to analyze the joint effects and interactions of mixed metal exposures. RESULTS: Findings revealed that higher levels of Zn (OR = 2.599, 95% CI: 1.096-6.164) and Fe (OR = 3.080, 95% CI: 1.277-7.431) were positively associated with the production of high-quality embryos, whereas elevated Ca (OR = 0.301, 95% CI: 0.126-0.718) and Cu (OR = 0.402, 95% CI: 0.171-0.949) levels correlated with lower oocyte maturation rates. Exposure to Pb was found to significantly reduce the rate of high-quality embryos (OR = 0.404, 95% CI: 0.170-0.964) and negatively affect clinical pregnancy outcomes (OR = 0.299, 95% CI: 0.123-0.726). Zn exhibited a significant positive correlation with Fe but a negative correlation with Ca, along with a positive association with LH, while lead showed negative correlations with both anti-Müllerian hormone (AMH) and estradiol (E2). CONCLUSIONS: These findings underscore the critical importance of considering metal exposure in relation to female fertility. Furthermore, additional research is necessary to elucidate the biological mechanisms linking metal elements in FF to the decline in female fertility.