Association between exposure to airborne particulate matter less than 2.5 μm and human fecundity in China

Background: Whether exposure to airborne particulate matter less than 2.5 mu m (PM2.5) could impact human fecundity is unclear. We aimed to evaluate the potential impact of PM2.5 exposure on time to pregnancy (TTP) and the prevalence of infertility in the general Chinese population. Method: We collected reproductive information, sociodemographic characteristics, and lifestyle data of 10,211 couples at risk of pregnancy from a large-scale community-based fertility survey in China. Then, we estimated each participant's 1-year, 3-year, and 5-year average PM2.5 exposure levels based on remote sensing information. After adjusting for demographic, lifestyle, and environmental co-variables, discrete-time Cox regression models were used to estimate the fecundability odds ratio (FOR) per 10 mu g/m(3) change of PM2.5. We also estimated the odds ratio (OR) of infertility per 10 mu g/m(3) change of PM2.5, using logistic regression models. Findings: Among the 10,211 couples, 6,875 (67%) had conceived spontaneously, with a median TTP of 5 months (interquartile range: 2-10 months). The median PM2.5 exposure was 56.8 mu g/m(3), with a wide range of 9.2-93.5 mu g/m(3). In Cox regression models, each increase of 10 mu g/m(3) in the 1-year average PM2.5 exposure was associated with a significant decrease in fecundity by 11% (FOR: 0.89; 95% confidence interval [CI]: 0.86-0.92). In logistic regression models, it was also associated with an 20% increased likelihood of infertility (OR: 1.20; 95% CI: 1.13-1.27). Conclusion: PM2.5 exposure was associated with reduced human fecundity, presented by a longer TTP and higher odds of infertility, which might explain the increased infertility rates in areas with heavy PM2.5 pollution.