Air Pollution Exposure in Early Pregnancy Linked To Miscarriage, Study Suggests

Exposure to common air pollutants, such as ozone and fine particles, may increase the risk of early pregnancy loss, according to a study.

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Ozone is a highly reactive form of oxygen that is a primary constituent of urban smog. Researchers followed 501 couples attempting to conceive between 2005 and 2009 in Michigan and Texas. The investigators estimated the couples’ exposures to ozone based on pollution levels in their residential communities. 

The researchers do not know why exposure to air pollutants might cause pregnancy loss, but it could be related to increased inflammation of the placenta and oxidative stress, which can impair fetal development. The findings suggest that pregnant women may want to consider avoiding outdoor activity during air quality alerts, but more research is needed to confirm this association.

The study was led by Dr. Pauline Mendola, an investigator at NICHD. Her team previously found that ozone increased the risk of stillbirth. Mendola and her colleagues have also examined the effects of air pollution and extreme temperatures on other adverse outcomes of pregnancy.