Fine Particulate Matter Air Pollution May Increase Preterm Birth Risks: Study

Exposure to fine particulate matter during the second trimester of pregnancy has been linked to a high rate of spontaneous preterm births.

New research suggests that pregnant women should try to reduce their exposure to air pollution, due to increasing evidence that particulate matter could harm their unborn child.

Particulate matter (PM 2.5) is a type of air pollution made up of ultra-tiny particles of soot, dirt and droplets, which are smaller than 2.5 micrometers, or 70 times smaller than the width of a single human hair. They may come from vehicle emissions, industry fumes or other sources of air pollution, and the microscopic particles can easily enter the airways and the bloodstream.

In findings published in the medical journal JAMA Network Open on November 13, researchers from the University of California, Irvine indicate that particulate matter may pose a much greater hazard for pregnant women than previously believed, with exposure during the second trimester increasing the potential for preterm birth, which can lead to a risk of severe illness or early death for the unborn child.

In this study, a team of researchers led by Dr. Anqi Jiao analyzed data on more than 409,000 births in Southern California from 2008 to 2018, using data from the Kaiser Permanente Southern California health network.

The data was compared to known levels of sulfate, nitrate, ammonium, organic matter and black carbon pollution that the mothers were exposed to during pregnancy, including an analysis of each trimester. The researchers also compared exposure to total green space, trees, low-lying vegetation and grass, as well as exposure to wildfires.

According to the findings, there is a clear link between exposure to fine particulate matter, black carbon, nitrate and sulfate and an increased risk of spontaneous preterm birth (sPTB). For every 25% increase in the level of exposure to the pollutants, there was a 15% increase in the risk of a pregnant woman experiencing preterm birth.

Preterm birth increases an infant’s risk of suffering a range of health conditions, including low birth weight and size, impaired respiratory function and slow growth.

Researchers determined the preterm birth risk was higher among people with lower income and lower education, those who experienced less green space, and those who were exposed to more wildfires and extreme heat. The risk of preterm birth linked to exposure to pollution was also higher during the second trimester of pregnancy compared to the first and third.

The findings come amid increasing evidence regarding a number of long-term health risks associated with exposure to air pollution. Due to risks faced in communities nationwide, the U.S. Environmental Protection Agency recently proposed a rule to reduce particulate matter in air pollution emissions, which would put a greater cap on the PM 2.5 that can be produced via manufacturing.

However, researchers said more must be done, emphasizing that there is a greater need for public health programs that can help promote healthy living among vulnerable groups. These include programs that can offer access to things that help reduce the risk, such as increased access to parks and green space, as well as health education.

“In this study, exposures to PM2.5 and specific PM2.5 constituents during pregnancy were associated with increased odds of sPTB,” Jiao’s team warned. “Socioeconomic status and other environmental exposures modified this association.”

Particulate Matter Linked to Numerous Health Risks

This is not the first warning from researchers about the dangers of particulate matter, particularly for pregnant women. Prior studies have linked particulate matter to a range of negative health effects.

Earlier this year, a study published by Harvard researchers linked prenatal exposure to PM 2.5 to an increased risk of cerebral palsy. Other studies have linked particulate matter exposure to cardiovascular disease and impaired respiratory function. Even at low levels PM 2.5 can pose a risk to children’s long-term mental health and cognitive function.

In addition, particulate matter has been linked to an increased risk of breast cancer, particularly among Black and Latina women, who potentially face a greater risk due to environmental factors rather than genetic reasons.