Fine particulate air pollution may play a role in adverse birth outcomes

The study will be published November 29 in Science Advances.

"This study represents a substantial step forward in understanding the biological pathways through which PM2.5 exposure affects pregnancy, maternal health, and fetal development. Its advanced methodology represents a significant innovation for how we study immune responses to environmental exposures," said corresponding author Kari Nadeau, John Rock Professor of Climate and Population Studies and chair of the Department of Environmental Health.

Previous research has found associations between exposure to PM2.5 and maternal and child health complications including preeclampsia, low birth weight, and developmental delays in early childhood. To understand these associations on a cellular level, the researchers used air quality data collected by the Environmental Protection Agency to calculate study participants' average PM2.5 exposure. Participants were both non-pregnant women and 20-week pregnant women. The researchers then used an innovative technology to understand how pollution modified the DNA of participants' individual cells. Within each cell they were able to map changes to histones, the proteins that help control the release of cytokines -- proteins that help control inflammation in the body and that can affect pregnancy.

The study found that PM2.5 exposure can influence the histone profiles of pregnant women, disrupting the normal balance of cytokine genes and leading to increased inflammation in both women and fetuses. In pregnant women, this increase in inflammation can correspond with adverse pregnancy outcomes.

"Our findings highlight the importance of minimizing air pollution exposure in pregnant women to protect maternal and fetal health," said co-author Youn Soo Jung, research associate in the Department of Environmental Health. "Policy interventions to improve air quality, as well as clinical guidelines to help pregnant women reduce their exposure to pollution, could have a direct impact on reducing pregnancy complications."

Other Harvard Chan authors were Abhinav Kaushik and Mary Johnson.

The study was funded by the National Institutes of Environmental Health Science (R01ES032253), the National Heart, Lung, and Blood Institute (R01HL081521), and the National Institutes of Health/Environmental Protection Agency (EPA R834596/NIEHS P01ES022849, EPA RD835435/NIEHS P20ES018173).