Air pollution is now linked to premature birth in the U.S., causing over 3% of these events, about 16,000 each year. The annual cost has reached $4.3 billion, according to a new study by the NYU Langone Medical Center in New York City (Particulate Matter Exposure and Preterm Birth: Estimates of U.S. Attributable Burden and Economic Costs, Trasande et al. 2016). Researchers say the costs include prolonged hospital stays, long-term use of medications for the infant, as well as lost economic productivity for the mother. The report also found that the number of premature births linked to air pollution was highest in urban counties. Air pollution, the research says, introduces toxic chemicals to the mother such as fine particulate matter, which in turn leads to a cascade of ill effects: immune system stress, a weakened placenta, preterm birth and a host of potential mental and physical disabilities for the baby.

In the weeks immediately after birth, premature infants often have difficulty breathing and digesting food. They can also encounter longer-term challenges such as impaired vision, hearing, and cognitive skills as well as social and behavioral problems. Pregnant women may want consider moving away from areas with heavy pollution or at least purchase air filters and close windows during high traffic periods.

“Air pollution comes with a tremendous cost, not only in terms of human life, but also in terms of the associated economic burden to society,” says Dr. Leonardo Trasande, a professor at the medical center who led the research. “It is also important to note that this burden is preventable, and can be reduced by limiting emissions from automobiles and coal-fired power plants.”

Dr. Trasande plans to share the findings with policymakers. He also says the number of premature births in the U.S. remains well above those of other developed countries. The report, published in Environmental Health Perspectives, is the first to trace the frequency and cost of premature births related to air pollution.