The tiny pollutants emitted by fossil fuel combustion and wildfires may be raising the risk of adverse birth outcomes, a study has found. Exposure to fine particulate matter (PM 2.5) can cause higher inflammation levels in pregnant people, potentially causing negative impacts to their children, according to the study, published Friday in Science. Previous research had already identified associations between exposure to PM 2.5 and maternal and child health issues, including preeclampsia, low birth weight and developmental delays in early childhood. But this latest study, conducted by a Harvard University-led research team in California, is the first to explore the relationship between these pollutants and maternal and fetal health on a single-cell level. BestReviews is reader-supported and may earn an affiliate commission. Best Prime Day 2024 Deals Best Black Friday deals to shop from home Top holiday discounts under $100 Apple products marked down for Black Friday Shop Now "This study represents a substantial step forward in understanding the biological pathways through which PM 2.5 exposure affects pregnancy, maternal health, and fetal development," corresponding author Kari Nadeau, a professor of climate and population studies at the Harvard T.H. Chan School of Public Health, said in a statement. PM 2.5 pollution — generated from the combustion of gasoline, oil, diesel fuel and wood — can come from a variety of sources, including motor vehicle exhaust, industrial processes, residential wood-burning and wildfires. Breathing in these particles can raise the risk of a variety of health problems, including heart disease, asthma and other respiratory conditions. To understand the links between PM 2.5 and birth outcomes on a cellular level, the researchers collected blood samples from 168 pregnant participants living in Fresno, Calif., at 20 weeks of gestation. As a basis of comparison, they also took samples from 151 age-matched, nonpregnant women in Fresno and the Bay Area. The researchers then used air quality data collected by the Environmental Protection Agency to calculate PM 2.5 exposure levels for the participants at one week, three weeks, six weeks and nine months prior to the blood collection. They then employed a method called cytometry — a laboratory technique used to measure cell count and characteristics — to monitor epigenetic changes: modifications to gene expression that results from behavioral or environmental factors, rather than from shifts in DNA sequence.   Within each cell, the scientists were able to map out changes to histones, proteins that help control the release of other proteins called cytokines, which help regulate inflammation and can impact pregnancy, according to the study. Ultimately, the researchers found that PM 2.5 exposure can affect histone patterns in pregnant individuals in a way that disrupts cytokine genes and causes increased inflammation in both parent and child. Such inflammation can then lead to adverse pregnancy outcomes, according to the study. “Our findings highlight the importance of minimizing air pollution exposure in pregnant women to protect maternal and fetal health,” co-author Youn Soo Jung, a research associate in environmental health at the Harvard Chan School, said in a statement. “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,” she added.