Nobles CJ, et al. - Given the likelihood of an increase in hypertension risk in relation to endothelial damage and oxidative stress caused by ambient air pollution, researchers sought for evidence regarding the effects of ambient air pollution on hypertension in pregnancy. Using Community Multiscale Air Quality models, criteria pollutant and volatile organic compound levels during pregnancy were determined among 49,607 women with at least 2 singleton deliveries in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Consecutive Pregnancies Study (2002–2010). Medical records were used to abstract gestational hypertension and preeclampsia diagnoses. The analysis revealed lower preeclampsia risk in correlation to higher levels of most criteria pollutants during preconception and the first trimester, while there was greater gestational hypertension risk in relation to higher second-trimester levels. Findings thereby further support the possible influence of air pollution on the development of hypertension in pregnancy, although these relationships may alter with different causes of preeclampsia and gestational hypertension.