Impacts of Ambient Fine Particulate Matter on Blood Pressure Pattern and Hypertensive Disorders of Pregnancy

Abstract

Ambient fine particulate matter (PM 2.5 ) exposure during pregnancy was associated with hypertensive disorders of pregnancy (HDP) in previous studies, however, the results were inconsistent. In addition, its effects on blood pressure (BP) pattern, which was different between normal pregnancy and pregnancy with HDP, remain unclear. In this study, we estimate daily PM 2.5 exposure levels of 7658 pregnant women from a prospective cohort study in Wuhan, China, using land use regression model. BP was repeatedly measured in each trimester. Linear mixed-effect model was used to examine associations of PM 2.5 exposure with BP patterns during pregnancy. The association between PM 2.5 exposure and HDP was estimated by modified Poisson regression. In the lowest quartile of PM 2.5 exposure, BP fell gradually during early pregnancy and increase subsequently after a nadir at mid-pregnancy. In higher quartiles of PM 2.5 exposure, a slower drop of BP was observed during early pregnancy, and the mid-pregnancy drop was less obvious compared with the lowest quartile. PM 2.5 exposure during the second trimester was positively associated with the risk of HDP (relative risk =1.42 [95% CI, 1.19–1.70]), especially among women with excessive gestational weight gain (relative risk =1.48 [95% CI, 1.16–1.90; P for interaction =0.03). Our study suggests that PM 2.5 exposure might play an important role in BP pattern during pregnancy and might increase the risk of HDP, especially among women with excessive gestational weight gain.