Associations between congenital heart disease and air pollutants at different gestational weeks: a time-series analysis

Exposure to air pollution during pregnancy has been linked to birth defects. But the directions of studies on the associations between air pollutants exposure and effect on the incidence of congenital heart disease (CHDs) were inconsistent. To date, few studies were concentrated on the effects of both particulate matter and gaseous air pollutant exposure on CHDs across the full gestational week simultaneously. Our study aimed to investigate the critical exposure windows for each air pollutant throughout 40 gestational weeks. Data on CHDs, air pollution, and meteorological factors from 2013 to 2019 were collected in Lanzhou, China. A distributed lag nonlinear model combined with a quasi-Poisson regression model was applied to evaluate the weekly exposure–lag–response association between air pollutants levels and CHDs, and the subgroup analyses were conducted by gender (baby boy and baby girl). The study included 1607 mother–infant pairs. The results demonstrated that exposure of pregnant women to particulate matter ≤ 5 μm (PM 2.5 ) at lag 1–4 weeks was significantly associated with the risk of CHDs, and the strongest effects were observed in the lag 1 week (1.150, 95%CI 1.059–1.248). For exposure to particulate matter ≤ 10 μm (PM 10 ) at lag 1–3 weeks, the strongest effects were observed in the lag 1 week (1.075, 95% CI 1.026–1.128). For exposure to sulfur dioxide (SO 2 ) at lag 1–4 weeks, the strongest effects were observed in the lag 1 week (1.154, 95% CI 1.025–1.299). For exposure to carbon monoxide (CO) at lag 1–3 weeks, the strongest effects were observed in the lag 1 week (1.089, 95% CI 1.002–1.183). For exposure to ozone (O 3 ) concentration at lag 9–15 weeks, the strongest effects were observed in the lag 15 weeks (1.628, 95% CI 1.001–2.649). The cumulative effects of PM 2.5 , PM 10 , SO 2 , and CO along weeks with a maximum of 1.609 (95%CI 1.000–2.589), 1.286 (95%CI 1.007–1.641), 1.648 (95%CI 1.018–2.668), and 1.368 (95%CI 1.003, 1.865), respectively. The effects were obvious in the initial gestational weeks too. Through the gender stratification analysis, the air pollutants with significant effects were PM 2.5 for baby boys and PM 2.5 , PM 10 , SO 2 , CO, NO 2 , and O 3 for baby girl. For the relationship between CHDs and air pollution in Lanzhou, PM 2.5 , PM 10 , SO 2 , CO, and O 3 played an important role in the initial gestational weeks, especially for baby girl.