Effect of environmental air pollution on spontaneous abortion in the main urban area of Chongqing from 2017 to 2019: a case-crossover study

Abstract

Objective To analyze the relationship between air pollutants and spontaneous abortion in Chongqing. Methods Time trend bias was controlled by time-stratified case-crossover design. The distribution lag nonlinear model was employed to study the relationship between air pollution and the number of spontaneous abortion in the main urban area of Chongqing and to control the influence of confounding factors such as meteorological factors. Based on the single pollutant model, the two-pollutant model was used to control the influence of other pollutants on correlation. Results During the study period, the average daily concentration of PM2.5, PM10, NO2 and SO2 in the air was 39.32, 63.31, 41.04 and 8.86μg/m3, respectively. All pollutants except NO2 were associated with the risk of spontaneous abortion, and all the associations reached the peak value at the lag of 3 d. For the increase of every 10μg/m3, the relative risk value was 1.069 (95%CI: 1.010~1.132), 1.046 (95%CI: 1.007~1.086) and 1.511 (95%CI: 1.148~1.989), respectively. These associations still existed in the two-pollutants model. Conclusion Short-term exposure of PM2.5, PM10 and SO2 in the ambient air may increase the risk of spontaneous abortion in Chongqing.

Keywords

• air pollution
• spontaneous abortion
• distributed lag non-linear model
• case-crossover study