Study finds how pollution can increase risk of inflammation, pregnancy complications

Exposure to PM2.5 pollution is linked to higher inflammation levels among pregnant women, which can potentially result in adverse birth outcomes, such as low birth weight and preterm birth, according to a study.

The findings, published in the journal Science Advances, provided a new understanding of the biological routes through which air pollution affects pregnancy and birth outcomes, researchers said.

Particulate matter (PM) 2.5 pollution is caused by particles sized 2.5 micrometres or less. Common sources are vehicular and industrial emissions, while natural ones can include carbon from wildfires and dust.

The study, led by Harvard University’s School of Public Health, US, found that exposure to PM2.5 can influence the histones of pregnant women. Histones are proteins found in chromosomes, vital to DNA structure and cell function.

Air pollution can, thus, disrupt the normal balance of cytokine genes –genes involved in producing immune responses- and lead to increased inflammation in both women and foetuses, the researchers said.

Among pregnant women, the increased inflammation could be related to adverse pregnancy outcomes, they said.

“Our findings highlight the importance of minimising air pollution exposure in pregnant women to protect maternal and foetal health,” co-author Youn Soo Jung, a research associate at Harvard University’s School of Public Health, said.

“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,” Soo Jung said.

While previous studies have found links between PM2.5 exposure and complications in maternal and child health including low birth weight and developmental delays, the study is the first to examine the effects of PM2.5 on maternal and foetal health at a cell level, the authors said.

The study involved both non-pregnant women and 20-week pregnant women. Average exposure to PM2.5 was calculated using air quality data from the US Environmental Protection Agency.

Within each cell, the researchers were able to map changes to histones -the proteins that help control the release of cytokines, which are known to help regulate inflammation.

“These modifications in specific histones and cytokines could indicate the toxicological mechanism of PM2.5 exposure in inflammation, inflammasome pathway, and pregnancy complications,” the authors wrote.