Association of maternal exposure to ambient particulate pollution with incident spontaneous pregnancy loss

Abstract

BackgroundMaternal exposure to ambient fine particulate matter (PM2.5) is a potential risk factor for pregnancy loss, but the extant findings are inconsistent. One reason for the inconsistency is the difficulty of distinguishing spontaneous from induced pregnancy losses, particularly in countries with planning policies. ObjectiveTo examine the association between maternal PM2.5 exposure and spontaneous incident pregnancy loss in China. MethodsA total of 18,513 women of reproductive age was recruited from Jiangsu Province, China, in 2007. Among them, 2451 women reported 2613 valid records of incident pregnancies from 2007 to 2010. We used Cox regression to link the outcomes (live birth, spontaneous pregnancy loss, or induced abortion) of those incident pregnancies with maternal PM2.5 exposures, assessed using well-developed estimates of historical concentrations at the county level. ResultsAmong the 2613 incident pregnancies, 69 spontaneous pregnancy losses, 596 induced abortions, and 1948 live births occurred. According to the adjusted model, each 10-μg/m3 increment in the average PM2.5 concentration during pregnancy was associated with a 43.3% (95% confidence interval, 6.6–92.5%) increased probability of spontaneous pregnancy loss. Advanced maternal age, a potential competing risk factor, weakened the association between PM2.5 and spontaneous pregnancy loss. The association was nonsignificant for unintended pregnancies. ConclusionMaternal PM2.5 exposure was associated significantly with incident spontaneous pregnancy loss. Our findings provide insight into the harmful effect of air pollution on human reproduction.