Houston traffic pollution linked to premature births

Pregnant women who live outside Houston's Interstate 610 loop and had longer work commutes were more likely to have preterm births than women living within the loop, according a new study from Baylor College of Medicine and Texas Children's Hospital.

The researchers wanted to see if exposure to chemicals from traffic pollution had a similar effect to that of maternal smoking, which has been shown to increase the risk of a preterm birth.

"Since we cannot easily measure those in any individual pregnant mom, we relied on a database where we recorded zip codes of where women live and where they work," said Dr. Kjersti Aagaard, associate professor of obstetrics and gynecology at Baylor and Texas Children's, and senior author of the study.

They collected information from more than 9,000 pregnancies and combined it with data on traffic exposure in the surrounding areas. The researchers found there was less traffic congestion in suburban areas, but most of the pregnant women living there commuted inside the loop and had longer commutes. As a result, they had more exposure to air and noise pollution.

Preterm birth rates were significantly higher for women living outside the 610 loop than for women living inside the loop. The study design did not allow the researchers to make any causal conclusions.

"It's important to know if there are factors that might lead to preterm birth that you can potentially mitigate or change," said Dr. Maike Kahr, a postdoctoral fellow of obstetrics and gynecology at Baylor and lead author of the study. "If ultimately we can demonstrate through several channels a link between vehicle exhaust and commuter routes with preterm birth, then communities may choose to invest in alternative commuter options."

About 10 to 12 percent of women in the United States deliver babies prematurely, a rate much higher than in other developed countries. Preterm babies are likely to need time in the neonatal intensive care unit and can often have lifelong respiratory and other health issues.

"It is very unique in the U.S. that preterm birth rates are so high, and we really don't know why," Kahr said.

The research, which was published in January in the American Journal of Obstetrics and Gynecology, was funded by Texas Children's and the March of Dimes Prematurity Research Initiative.