Ambient Air Pollution Exposure and Fecundability in Women Undergoing in Vitro Fertilization

Abstract

Background: Limited research suggests ambient air pollution impairs fecundity but groups most susceptible have not been identified. We studied whether long-term ambient air pollution exposure before an in vitro fertilization (IVF) cycle was associated with successful livebirth, and whether associations were modified by underlying infertility diagnosis. Methods: Data on women initiating their first autologous IVF cycle in 2012-2013 were obtained from four US clinics. Outcomes included pregnancy, pregnancy loss, and livebirth. Annual average exposure to fine particulate matter (PM2.5), PM10, and nitrogen dioxide (NO2) before IVF start were estimated at residential address using a validated national spatial model incorporating land-use regression and universal kriging. We also assessed residential distance to major roadway. We calculated risk ratios (RR) using modified Poisson regression and evaluated effect modification (EM) by infertility diagnosis on additive and multiplicative scales. Results: Among 7,463 eligible participants, 36% had a livebirth. There was a nonsignificant indication of an association between PM2.5 or NO2 and decreased livebirth and increased pregnancy loss. Near-roadway residence was associated with decreased livebirth (RR = 0.96, 95% CI = 0.82, 0.99). There was evidence for EM between high exposure to air pollutants and a diagnosis of diminished ovarian reserve (DOR) or Male infertility and decreased livebirth. Conclusions: Despite suggestive but uncertain findings for the overall effect of air pollution on fecundity, we found a suggestive indication that there may be synergistic effects of air pollution and DOR or Male infertility diagnosis on livebirth. This suggests two possible targets for future research and intervention.