Air pollution exposure and ovarian reserve impairment in Shandong province, China: The effects of particulate matter size and exposure window

Background: Lack of evidence exists on whether air pollution exposure may affect ovarian reserve, especially for Chinese women. Objectives: To explore the association between exposure to various air pollutants and anti-Müllerian hormone (AMH), a predictor of ovarian reserve, over different exposure windows in Shandong Province, China. Methods: We enrolled 18,878 women who had AMH measurements in the Center for Reproductive Medicine, Shandong University during 2010–2019. Daily average concentrations of ambient particulate matter with diameters ≤1 μm/2.5 μm/10 μm (PM₁, PM_2.5, and PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) were developed at a spatial resolution of 0.01° × 0.01°, and assigned to the residential addresses. Three exposure windows were considered, i.e., the process from primary to small antral follicle stage (W1), from primary to secondary follicle stage (W2), and from secondary to small antral follicle stage (W3). The air pollution-AMH association was fitted using the multivariable linear mixed effect model with adjustment for potential confounders. Stratified analyses were performed by age group, overweight status, residential region, and educational level. Results: The level of AMH changed by −8.8% (95% confidence interval (CI): −12.1%, −5.3%), −2.1% (95% CI: −3.5%, −0.6%), −1.9% (95% CI: −3.3%, −0.5%), and −4.5% (95% CI: −7.1%, −1.9%) per 10 μg/m³ increase in PM₁, PM_2.5, PM₁₀, and NO₂, respectively, during W1. The effect estimates were significant during W2 for PM₁, PM_2.5 and NO₂ while minimal association was observed in W3. Greater vulnerability for certain air pollutants were observed for women who lived in inland areas and were less educated. Conclusions: We found that ovarian reserve was negatively associated with air pollution exposure for women, particularly from the primary to secondary follicle stage. The effect estimate increased by the reduction in the diameter of PMs, which also varied across population sub-groups.