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02-04-2013 | Gynaecology | Article

Air pollution increases neural tube defect risk for unborn babies


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medwireNews: A high level of exposure to air pollution in early pregnancy significantly increases the risk for congenital birth defects, suggest US study findings published in the American Journal of Epidemiology.

"We found an association between specific traffic-related air pollutants and neural tube defects, which are malformations of the brain and spine," the study's lead author Amy Padula (Stanford University, California) told the press.

Women in the highest versus the lowest quartiles for exposure to the air pollutants carbon monoxide, nitrogen oxide, and nitrogen dioxide in early pregnancy had a significant 90%, 80%, and 70% increased risk for giving birth to a child with neural tube defects (spina bifida and anencephaly), respectively, following adjustment for factors such as maternal ethnicity, education, and multivitamin use.

Notably, high ozone exposure seemed to decrease the risk for neural tube defects, but in mothers aged 20 years or older being in the highest versus the lowest quartile for exposure increased the adjusted risk for gastroschisis 2.1 fold. No links between traffic pollutant exposure and cleft lip or palate were observed.

"Birth defects affect one in every 33 babies, and about two-thirds of these defects are due to unknown causes," said co-author Gary Shaw, also from Stanford University, in a press statement.

"When these babies are born, they bring into a family's life an amazing number of questions, many of which we can't answer."

For their study, Padula and team assessed women from the San Joaquin Valley of California who gave birth between 1997 and 2006. In total, 806 of the babies born in this area during this period had congenital birth defects - 215 neural tube defects, 293 cleft lip and/or palate, 129 cleft palate only, and 169 gastroschisis. A group of 849 babies without birth defects were also included for control purposes.

To assess levels of air pollution in general, as well as levels of individual pollutants, the researchers analyzed air pollution measurements and traffic metrics for locations at which the participating mothers lived during the first and second months of their pregnancies.

"If these associations are confirmed, this work offers an avenue for a potential intervention for reducing birth defects," Padula said.

"In addition, for our colleagues who are bench scientists, this work gives them an opportunity to think about what pollution exposures might mean mechanistically," Shaw added. "It could give them a better understanding of the details of human development."

By Helen Albert, Senior medwireNews Reporter

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