Mother Earth: Pollution Impacts Pregnancy

Breathing traffic pollution in early pregnancy is linked to higher risk for certain serious birth defects, according to new research from the Stanford University School of Medicine.

The finding comes from a study examining air quality and birth-defect data for women living in California’s San Joaquin Valley, one of the smoggiest regions of the country. “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 at Stanford. The research was published online March 28 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. “When these babies are born, they bring into a family’s life an amazing number of questions, many of which we can’t answer.” Shaw is a research professor of pediatrics in neonatal and developmental medicine at Stanford.

The scientists studied 806 women who had a pregnancy affected by a birth defect between 1997 and 2006, and 849 women who had healthy babies during the same period.

All women studied resided in an area of California known for poor air quality –  the San Joaquin Valley – during the first 8 weeks of their pregnancies, a window of time when many birth defects develop. Women who breathed the highest levels of carbon monoxide were nearly twice as likely to have a baby with spina bifida or anencephaly as those with the lowest carbon monoxide exposure. Nitrogen oxide and nitrogen dioxide exposures were also linked to increased risk for these defects; women with the highest nitrogen oxide exposure had nearly three times the risk of having a pregnancy affected by anencephaly, for example. Further studies are needed to examine the combined effects of multiple pollutants, and to examine other pollutants, as well as other types of birth defects, the researchers said.

“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 said. “It could give them a better understanding of the details of human development.”