Women exposed to air pollution from freeways and congested roads are much more likely to give birth to premature babies and suffer from preeclampsia, according to a study by University of California scientists published Wednesday.
The findings, based on pregnant women in the Long Beach/Orange County region of Southern California, add to the growing evidence that car and truck exhaust can jeopardize the health of babies while they are in the womb.
Reviewing the birth records of more than 81,000 infants, researchers found that the risk of having a baby born before 30 weeks of gestation increased 128 percent for women who live near the worst traffic-generated air pollution.
In addition, preeclampsia increased 42 percent for women who lived in those areas, according to the study, published online in the scientific journal Environmental Health Perspectives. Preclampsia, a serious illness that involves high blood pressure, can endanger the baby and the mother.
The team of scientists from UCLA and University of California, Irvine studied babies born in Long Beach, near the Ports of Los Angeles and Long Beach, and in adjacent Orange County. Those areas are traversed by several major freeways used by commuters as well as heavy-duty trucks delivering goods to and from the ports.
The infants’ birth records were matched with their addresses and then compared with traffic patterns and estimates of two pollutants—particulates and nitrogen oxides—from vehicles near the mothers’ homes.
The study was unique in that the researchers constructed a database estimating what the pregnant women breathed in their own neighborhoods--within three kilometers, or less than two miles, of their homes. Previous studies have used general air pollution measurements, which is a less accurate estimate of what people are exposed to.
Only traffic-generated emissions were included in the study, not pollutants from factories and other sources.
Fetuses “are in a very sensitive stage of development” that could be vulnerable to the toxic substances inhaled by their mothers, said Jun Wu, an assistant professor of epidemiology at UC Irvine and the study’s lead author.
Other recent studies have linked air pollutants to preterm births and low birth weights. But until now, “no study has associated air pollution with preeclampsia. This is the first one,” Wu said.
Tracey Woodruff, director of University of California, San Francisco’s Program on Reproductive Health and the Environment, said the research offers a relatively “new twist on air pollution,” since most scientists have focused on respiratory and cardiovascular diseases.
“This is just one more piece of the scientific evidence that air pollution can have effects on adverse pregnancy outcomes,” said Woodruff, who was not involved in the research.
The babies in the study were born between 1997 and 2006 at four hospitals: Long Beach Memorial and three in Orange County--Anaheim Memorial, Orange Coast Memorial in Fountain Valley and Saddleback Memorial in Laguna Hills.
Maria Gugerty, a Long Beach resident, said she always has wondered what might have caused her son, Will, to be born premature, at 31 weeks. Her son was likely one of the preemies reviewed in the study since he was born at Long Beach Memorial in 1997.