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Birth defects linked to air pollution in new Stanford study

Here's a new reason to dislike smog: Air pollution from traffic has been linked to birth defects in a large new Stanford study of women who lived in California's smoggy San Joaquin valley during the early weeks of their pregnancies.

From our press release on the study:

“We found an association between specific traffic-related air pollutants and neural tube defects, which are malformations of the brain and spine,” said the study’s lead author, Amy Padula, PhD, a postdoctoral scholar in pediatrics. The research appears online today in the American Journal of Epidemiology.

“Birth defects affect one in every 33 babies, and about two-thirds of these defects are due to unknown causes,” said the paper’s senior author, Gary Shaw, PhD, professor of neonatal and developmental medicine. “When these babies are born, they bring into a family’s life an amazing number of questions, many of which we can’t answer.”

The new research focused on five structural birth defects thought to be potentially affected by the mother's environment during pregnancy, as well as seven pollutants measured during the EPA's federally mandated monitoring of air quality. The researchers compared more than 800 women who had a pregnancy affected by a birth defect between 1997 and 2006 to a similar number of women who had healthy babies during the same period. All of the women lived in the San Joaquin valley during their first eight weeks of pregnancy, and each gave the researcher her home address so that her pollution exposure could be estimated using data from nearby EPA air-quality monitoring stations.

The study is just the beginning of researchers' efforts to understand the effects of traffic pollution on fetal development. Although a few prior studies have suggested a possible link, they have focused on different geographic regions, have produced conflicting results and have had various flaws in their methods. The new study is the first, for instance, to evaluate women's pollution exposure in early pregnancy, when birth defects are likely to be developing, rather than at birth.

Much work is still needed in this area, the scientists say, including widening the scope of birth defects studied and examining the effects of combinations of pollutants. If future studies support the new findings, they could offer a route for preventing some devastating birth defects.

Previously: Better diet in pregnancy shown to protect against birth defects, NIH study supports screening pregnant women for toxoplasmosis and Federal government tests potential health risks of 10,000 chemicals using high-speed robot
Photo by Lynn Friedman

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