Association between exposure to air pollutants and risk of infertility in men of childbearing age: a PREBIC cohort study in Chongqing

To investigate the association between exposure levels of air pollutants（PM₁₀, PM_2.5, SO₂, O₃, NO₂, and CO）and infertility risk in men of childbearing age.

Preconception Reproductive Health and Birth Outcomes Cohort（PREBIC）was subjected by recruiting men of childbearing age who taking pre-pregnancy health examination in Chongqing Maternal and Child Health Hospital since November 2018. The baseline indicators were collected and established after their enrollment. Then they were followed up every 3 months, and failure to achieve a clinical pregnancy after 12 months of unprotected intercourse was defined as infertility. The individualized air pollution exposure levels of the subjects in 3 months prior to enrollment（spermatogenic cycle）were assessed by machine learning algorithm. Logistic regression model was established to determine the effect of air pollutant exposure on infertility and the potential susceptibility windows induced by single pollutant. Sensitivity analysis was carried out using two-pollutant model. The joint effects and interaction of air pollutants on infertility were analyzed by Bayesian kernel machine regression.

A total of 2 297 male subjects were included in the study. After multiple test adjustment, the relative risk of infertility was increased by 29.3%（OR=1.293, 95%CI: 1.022-1.636, P=0.008）in the highest and lowest quartiles of PM₁₀ exposure during the 90 d prior to enrollment. In the analysis of susceptibility windows, PM₁₀ was associated with infertility at all stages from 0 to 90 d, and no significant susceptibility window was observed. No significant results were observed in the analysis of the joint effects and interactions of air pollutants.

Male exposure to PM₁₀ may increase the risk of infertility.