Exposure to ambient air pollution may place pregnant women at an increased risk of having a stillbirth, according to the findings of a new study that provides further evidence about the potential health impact of common pollutants.
In a study published last week in the medical journal Occupational & Environmental Medicine, researchers from Finland concluded that exposure to ambient air pollution, in particular exposure to small particulate matter, increased a woman’s chance of having a stillbirth by two percent.
While the size of the effect may seem small, the researchers note that the ubiquitous nature of ambient air pollution in the environment and the constant exposure many pregnant women face, suggests that air pollution may have a significant impact on stillbirth rates among the greater population.
Researchers conducted a meta-analysis of data from 13 studies that focused on air pollution and stillbirths. They searched three databases, PubMed, Scopus, and Web of Science from time of inception to mid-April 2015.
The findings indicate an association between air pollution and stillbirths, particularly when the exposure occurred during third trimester of pregnancy. A 4 microgram increase in exposure to small particulate matter of less than 2.5 micrometers diameter (PM 2.5) was associated with a two percent increased risk of stillbirth.
Exposure to nitrogen dioxide, carbon monoxide, particulate matter 10 micrometers in diameter and ozone were also linked to heightened risk of suffering a stillbirth. Among women who had stillbirths the levels of sulfur dioxide, carbon monoxide, particulate matter less than 10 micrometers in diameter, and ozone were the highest for the third trimester exposure.
Another study published earlier this year concluded prenatal exposure to air pollution may affect a child’s ability to get along with others and control their emotions or impulses. Exposure levels common in many countries around the world, may have lasting effects on children, according to the findings. Another study linked air pollution exposure, even for short periods, to increased risk of stroke.
Critics say the findings of the new study are suggestive evidence that air pollution is linked to an increased risk of stillbirth; however most of the existing evidence relies on air monitoring data, which doesn’t adequately capture variations in levels within the same city.
Another study published in the American Journal of Public Health revealed minority families may be more likely to live in the path of harmful air pollution. The study supported the long-standing environmental justice assumptions that big polluters specifically target minority populations, placing them at higher risk for health problems.
An estimated 2.6 million children worldwide were stillborn at 28 weeks or more in 2015, and health experts say most of the deaths were preventable.
“The body of evidence suggests that exposure to ambient air pollution increases the risk of stillbirth,” wrote study authors. “Further studies are needed to strengthen the evidence.”