Ozone exposure increases gestational hypertension risk during first trimester
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Key takeaways :
- Each 10 µg/m3 ozone exposure increment in early pregnancy raised gestational hypertension risk.
- Weeks 1 to 9 gestation had highest susceptibility for ozone exposure and gestational hypertension risk.
Ozone exposure was associated with an increased risk for gestational hypertension during the first trimester of pregnancy, according to a cohort study published in JAMA Network Open.
“An increasing number of studies have revealed that exposure to air pollutants, such as fine particulate matter and nitrogen dioxide, was associated with a higher risk of hypertension in the general population,” Yukai Cheng, MS, from the Key Laboratory of Health Technology Assessment, National Health Commission of the People’s Republic of China, Fudan University, Shanghai, and colleagues wrote. “Pregnancy is a unique period for individuals, producing rapid changes in blood volume, cardiac output and maternal heart rate. Compared with the general population, pregnant individuals are more vulnerable to environmental contaminants.”
Researchers recruited 7,841 pregnant participants (mean age, 30.4 years) from March 2017 to December 2018 from the Obstetrics and Gynecology Hospital of Fudan University in Shanghai. All participants were adult Shanghai residents with no infectious diseases or chronic noncommunicable diseases prior to pregnancy. Researchers diagnosed gestational hypertension and preeclampsia based on diagnostic criteria from the Chinese Society of Obstetrics and Gynecology and predicted individual levels of daily ozone exposure during pregnancy using a high temporospatial resolution model.
The primary outcomes were gestational hypertension and preeclampsia diagnoses during pregnancy linked to ozone exposure.
Overall, 3.2% of participants had gestational hypertension and 5.2% had preeclampsia. Pregnant women with hypertensive disorders in pregnancy experienced higher prepregnancy BMI and lower educational levels compared with women without.
Mean ozone exposure levels were 97.66 µg/m3 during the first trimester and 106.13 µg/m3 during the second trimester of pregnancy. Researchers noted that each 10 µg/m3 increment of ozone exposure during the first trimester was associated with a higher risk for gestational hypertension (RR = 1.28; 95% CI, 1.04-1.57). Conversely, gestational ozone exposure was not associated with preeclampsia risk.
In addition, when conducting the restricted cubic spline function analysis, researchers observed an exposure-response association between ozone exposure and gestational hypertension risk.
“The findings indicated that gestational weeks 1 to 9 were the window of susceptibility for ozone exposure and elevated gestational hypertension risk,” the researchers wrote. “Sustainable ozone control is needed to reduce the disease burden of gestational hypertension.”