Long-term effect of fine particulate matter constituents on reproductive hormones homeostasis in women attending assisted reproductive technologies: A population-based longitudinal study.

Fine particulate matter (PM) may disrupt women's reproductive hormones, posing potential reproductive risks. However, the exact compositions of PM responsible for these effects remain unclear. Our investigation explored the long-term impacts of PM constituents on reproductive hormones, based on a large longitudinal assisted reproductive cohort study in Anhui, China. We included 24,396 reproductive hormone samples from 19,845 women attending assisted reproductive technologies (ART) between 2014 and 2020. Using high-resolution gridded data (1-km resolution), we calculated the residence-specified PM constituents during the year before the month of hormone testing. Relationships between PM constituents [organic matter (OM), chloride (Cl), sulfate (SO), ammonium (NH), black carbon, and nitrate] and reproductive hormones were investigated using the linear mixed model with subject-specific intercepts. The constituent-proportion model and the constituent-residual model were also constructed. Additionally, cubic spline analysis was used to examine the potential non-linear exposure-response relationship. We found that per interquartile range (IQR) increment in OM was associated with a 5.31 % (3.74 %, 6.89 %) increase in estradiol, and per IQR increment in Cl and NH were associated with 13.56 % (7.63 %, 19.82 %) and 9.07 % (4.35 %, 14.01 %) increases in luteinizing hormone. Conversely, per IQR increment in OM and Cl were associated with -7.27 % (-9.34 %, -5.16 %) and -8.52 % (-10.99 %, -5.98 %) decreases in progesterone, and per IQR increment in SO was associated with a -9.15 % (-10.31 %, -7.98 %) decrease in testosterone. These associations were held in both proportional and residual models. Moreover, exposure-response curves for estradiol and progesterone with PM constituents exhibited approximately U-shaped. These results suggested that specific PM constituents might disrupt reproductive hormone homeostasis in women attending ART, providing new evidence for formulating PM pollution reduction strategies that could benefit women's reproductive health.