Ambient air pollution exposure and blood pressure changes during pregnancy

Maternal exposure to ambient air pollution has been associated with adverse birth outcomes such as preterm delivery. However, only one study to date has linked air pollution to blood pressure changes during pregnancy, a period of dramatic cardiovascular function changes.

We examined whether maternal exposures to criteria air pollutants, including particles of less than 10 μm (PM(10)) or 2.5 μm diameter (PM(2.5)), carbon monoxide (CO), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), and ozone (O(3)), in each trimester of pregnancy are associated with magnitude of rise of blood pressure between the first 20 weeks of gestation and late pregnancy in a prospectively followed cohort of 1684 pregnant women in Allegheny County, PA.

Air pollution measures for maternal ZIP code areas were derived using Kriging interpolation. Using logistic regression analysis, we evaluated the associations between air pollution exposures and blood pressure changes between the first 20 weeks of gestation and late pregnancy.

First trimester PM(10) and ozone exposures were associated with blood pressure changes between the first 20 weeks of gestation and late pregnancy, most strongly in non-smokers. Per interquartile increases in first trimester PM(10) and O(3) concentrations were associated with mean increases in systolic blood pressure of 1.88 mm Hg (95% CI=0.84 to 2.93) and 1.84 (95% CI=1.05 to 4.63), respectively, and in diastolic blood pressure of 0.63 mm Hg (95% CI=-0.50 to 1.76) and 1.13 (95% CI=-0.46 to 2.71) in non-smokers.

Our novel finding suggests that first trimester PM(10) and O(3) air pollution exposures increase blood pressure in the later stages of pregnancy. These changes may play a role in mediating the relationships between air pollution and adverse birth outcomes.