Adding to the growing evidence about harmful effects of air pollution on health, a new study from China published online April 3, 2023 in the journal JAMA Network Open has demonstrated an association between risk of gestational hypertension and exposure to high ozone levels during the first trimester of pregnancy.¹ However, ozone exposure was not associated with risk of preeclampsia.

The study enrolled 7841 pregnant women, mean age 30.4 years, from a hospital in Shanghai in China between March 2017 and December 2018. The objective was to investigate if the exposure to ozone during pregnancy influenced the risk of gestational hypertension and preeclampsia. None of the participants had any noncommunicable disease prior to becoming pregnant. The mean ozone exposure levels were 97.66 μg/m3 in the first trimester and 106.13 μg/m3 in the second trimester.

Out of the 7841 women included in the study, 661 developed a hypertensive disorder; 406 (5.2%) had preeclampsia and 255 (3.2%) had gestational hypertension. The pre-pregnancy BMI was significantly higher among the women with hypertensive disorders in pregnancy. These women were also not well-educated. The risk of gestational hypertension increased by 28% with every 10 μg/m3 rise of ozone exposure during early pregnancy with a relative risk of 1.28. But no such association was noted for preeclampsia. Weeks 1 to 9 were identified as a highly susceptible period for exposure to ozone and high risk of gestational hypertension. “Sustainable O3 control is needed to reduce the disease burden of gestational hypertension”, conclude the authors.

Reference

1. Yukai Cheng, et al. Ozone exposure during pregnancy and risk of gestational hypertension or preeclampsia in China. JAMA Netw Open. 2023 Apr 3;6(4):e236347. doi: 10.1001/jamanetworkopen.2023.6347.