Common Air Pollutants Associated With Increased Risk of Pregnancy Loss Interview with:
“Cairo Air Pollution with smog - Pyramids1” by Nina Hale is licensed under CC BY 2.0Pauline Mendola, PhD

Epidemiology Branch
Division of Intramural Population Health Research
Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH
Bethesda, MD  20892 What is the background for this study? What are the main findings?

Response: We compared ambient air pollution levels at the residences of couples who were trying to get pregnant and estimated the risk of pregnancy loss associated with common pollutants. No prior studies have been done in the United States and most studies are retrospective, looking back in time, and asking couples to report on their reproductive outcomes. Without detailed prospective follow-up, early pregnancy losses that occur before entry into care (i.e., before women are aware that they are pregnant) are often missed. In contrast, we studied 501 couples in the Longitudinal Investigation of Fertility and the Environment (LIFE) study who were enrolled before pregnancy and followed until they became pregnant or tried for 12 months without a pregnancy. Using this prospective data, we found that both ozone and fine particles (PM2.5) were associated with a 12-13% increased risk of early pregnancy loss. What should readers take away from your report?

Response: Early pregnancy loss is common, occurring in 28% of couples in our study. Our findings suggest that exposure to common air pollutants is associated with increased risk of pregnancy loss. If the findings are confirmed, approximately 9 of the 98 losses in our study could potentially have been prevented if exposure to ozone and particles were lower. What recommendations do you have for future research as a result of this study?

Response: We would like to see these findings corroborated in other, larger studies and more work needs to be done on the underlying biologic mechanisms that link common air pollutants and pregnancy losses. Is there anything else you would like to add?

Response: Even though our study does not provide a causal link, it seems prudent for pregnant women to avoid outdoor activities when there are air pollution advisories, similar to the recommendations for people with asthma and other respiratory diseases.

This project was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Thank you for your contribution to the community.


Ha S, et al., Ambient air pollution and the risk of pregnancy loss: a prospective cohort study. Fertility and Sterility DOI: 10.1016/j.fertnstert.2017.09.037(link is external) (2017)

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions. 

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Last Updated on November 21, 2017 by Marie Benz MD FAAD