Ambient PM2.5 and its chemical constituents exposure with ovarian reserve among 29,610 infertile women in Shaanxi Province, China

Fine particulate matter (PM _2.5 ) has been suggested as a potential risk factor for female reproductive health. However, studies on specific PM _2.5 constituents and ovarian reserve remain limited. Moreover, the vulnerable time windows of air pollution exposure are not well understood. We aimed to evaluate the relationship between PM _2.5 constituents and ovarian reserve in China. This study included 29,610 women aged 20-45 years who underwent assisted reproductive technology treatment at a reproductive medicine center in Shaanxi Province, China, between 2015 and 2020. Residential PM _2.5 and five key constituents, including sulfate (SO ₄ ²⁻ ), nitrate, ammonium, organic matter, and black carbon exposure across five stages of follicle development, were estimated using satellite models. Generalized linear regression was applied to analyze the relationship between PM _2.5 constituent exposure during each stage and ovarian reserve indicators, including antral follicle count and anti-Müllerian hormone. Exposure to PM _2.5 was related to decreased antral follicle count across several periods, most notably during the period from the primordial to secondary follicle stage. The adjusted β ranged from −0.123 (95% confidence interval: −0.232, −0.013) for period 3 (primary follicle to secondary follicle) to −0.190 (95% confidence interval: −0.295, −0.085) for period 1 (primordial to small antral follicle). The constituent-residual model suggested that SO ₄ ²⁻ was most strongly related to impaired ovarian reserve. The robustness of the results was proved by additional sensitivity analyses. These relationships were more pronounced among women with lower educational levels. Our findings underscore the public health importance of mitigating air pollution to improve female reproductive health.