Exposure and perception of PM2.5 pollution on the mental stress of pregnant women

Prenatal exposure to ambient PM2.5 has been proved to be related to pregnant women's physical health and birth outcomes. However, the damage from air pollution on pregnant women's mental health has not been fully discussed. A case-control study was conducted to evaluate the effects of PM2.5 exposure and risk perception on the mental stress of pregnant women. A total of 605 pregnant women, including 403 high symptoms of stress cases and 202 matched controls, were recruited from January 2018 to December 2018 in Nanjing, among which 313 high symptoms of stress cases and 144 matched controls were included in the analysis. Meaningfully high symptoms of anxiety were defined with a score of 6 points or greater on the phobic anxiety subscale of the Crown-Crisp index. We found that the PM2.5 effect perceived by the case group was significantly higher than the control group, and the PM2.5 exposure of the case group was also significantly higher than that of the control group. Binary logistic regression showed that for each increase in unit of PM2.5 exposure, the risk of pregnant women suffering from high mental stress increased by 13.76% (95 %CI: 8.26-19.53%). Through path analysis modeling, we found that in the case group, perceived indoor attributions not only had a direct impact on mental stress (p < 0.001), but also played a key mediating role in the impact of average daily dose of PM2.5 on mental stress (p < 0.001). The high level of mental stress is not only affected by objective exposure, but also by subjective perceptions in the case group. Considering the significant effect of PM2.5 exposure on mental stress, pregnant women are recommended to spend appropriate amounts of time outdoors during clean air days. In addition, the mediating role of risk perception cannot be ignored. It is necessary to reassure pregnant women not to become overly concerned about the risk of PM2.5 pollution and reduce their psychological burden.