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

In pregnant women, exposure to fine particulate air pollution (PM2.5) was associated with altered immune responses that can lead to adverse birth outcomes, according to a new study led by the Harvard TH Chan School of Public Health. The study is the first to examine the relationship between PM2.5 and maternal and fetal health at the single-cell level and highlights the health risk of PM2.5 exposure to pregnant women.

The study is published in Scientific progress.

“This study represents a substantial step forward in understanding the biological pathways through which PM2.5 exposure affects pregnancy, maternal health and fetal development. The cutting-edge methodology represents a major innovation in how we understand immune responses to studying environmental exposure,” said corresponding author Kari Nadeau, John Rock Professor of Climate and Population Studies and chair of the Department of Environmental Health.

Previous research has shown links between PM2.5 exposure and health complications for mother and child, including preeclampsia, low birth weight and developmental delays in early childhood. To understand these associations at the cellular level, the researchers used air quality data collected by the Environmental Protection Agency to calculate the average PM2.5 exposure of the study participants. Participants included both non-pregnant women and women who were 20 weeks pregnant.

The researchers then used an innovative technology to understand how pollution changed the DNA of the participants’ individual cells. Within each cell, they were able to map changes in histones, the proteins that help control the release of cytokines – proteins that help control inflammation in the body and can influence pregnancy.

The study found that exposure to PM2.5 can affect 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 may be associated with adverse pregnancy outcomes.

“Our findings highlight the importance of minimizing exposure to air pollution in pregnant women to protect the health of mothers and fetuses,” said co-author Youn Soo Jung, research associate at 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 included Abhinav Kaushik and Mary Johnson.