With estimates suggesting that one in every eight babies in the U.S. is born premature, preterm births are a serious public health issue. New research suggests traffic-related air pollution might play a role, significantly increasing the risk of giving birth before 37 weeks.
Researchers with the University of California analyzed the birth certificates of children born to Los Angeles women living near several air quality monitoring stations. They found that exposure to traffic-related pollutants was associated with a 30 percent increased risk of preterm birth.
The new study highlighted polycyclic aromatic hydrocarbons (PAHs) as a pollutant of particular concern.
"Air pollution is known to be associated with low birth weight and premature birth," said Beate Ritz, a professor in the department of epidemiology at UCLA's School of Public Health and one of the study's authors, in a statement. "Our results show that traffic-related PAH are of special concern as pollutants, and that PAH sources besides traffic contributed to premature birth."
Patrick Ryan, a professor in the environmental health department at the University of Cincinnati, explained that PAHs can be formed by burning substances that contain carbon and hydrogen, such as wood and kerosene as well as gas and diesel fuel. He said that PAHs from traffic can be attached to fine particles that are easily inhaled into the body.
"Mechanistically, they can contribute to oxidative stress and inflammation in the body, which could lead to many adverse outcomes -- including low birth weight," Ryan told HuffPost.
But PAHs aren't the only cause for concern; the new study also suggested that pollutants such as benzene -- a known carcinogen emitted in car exhaust fumes -- are linked with increased preterm risk, as are ammonium nitrate particles.
So what does this all mean for expectant moms?
Dr. Michael Katz, senior vice president for research and grants at the March of Dimes, which works to promote full-term pregnancies, acknowledged that many women can't do much in terms of avoiding traffic. He explained, however, that pregnant women can and should take steps to avoid other sources of air pollution, particularly secondhand smoke.
Ryan added that pregnant women should not idle their cars and, if possible, should not live too close to major roads, as distance from the source of pollutants is important.
According to Ritz, pregnant women can further mitigate the potential effects of traffic pollution by eating well.
"Women can eat plenty of fruits and vegetables, particularly cruciferous vegetables like broccoli," she said. (Other cruciferous vegetables include cabbage, Brussels sprouts and kale.) "They can induce detoxification mechanisms in your body," Ritz added.
Above all, the experts agreed that, despite the association between traffic-related air pollution and premature births, women should not panic. They should focus on doing what they can to maintain a health pregnancy by, among other things, seeking out early and regular prenatal care and avoiding smoking and alcohol. And they should bear in mind that even women who do everything "right" can still give birth early.
"This study is not cause for alarm," said Katz. "It's simply a recognition that we don't live in a pure environment."