Associations between air pollution exposure and birth defects: a time series analysis

Air pollution is a serious environmental problem in China. Birth defects are particularly vulnerable to outdoor air pollution. Our study was to evaluate the association between short-term exposure to air pollutants and the risk of birth defects. Daily data including the air pollutants, meteorological characteristics, and birth records were obtained in Hefei, China, during January 2013 to December 2016. The findings showed that PM2.5, PM10, SO2, NO2, and O3 exposures were positively correlated with the risk of birth defects. Maternal exposure to PM2.5 and SO2 during the 4th to 13th gestational weeks was observed to have a significant association with the risk of birth defects, with the maximum effect in the 7th or 8th week for PM2.5 and the maximum effect in the 7th week for SO2. The positively significant exposure windows were the 4th to 14th weeks for PM10, the 4th to 12th weeks for NO2, and the 26th to 35th weeks for O3, respectively. The strongest associations were observed in the 8th week for PM10, the 7th week for NO2, and in the 31st or 32nd week for O3. The findings of this study demonstrate that air pollutants increase the risk of birth defects among women during pregnancy in Hefei, China, which provide evidence for improving the health of pregnant women and neonates in developing countries, and uncovered potential opportunities to reduce or prevent birth defects by proactive measures during pregnancy.