The study, published in the American Journal of Epidemiology, found every 10-fold increase in the levels of polybrominated diphenyl ethers in a mother's blood during pregnancy corresponded to a 4.1 ounce drop in her baby's birth weight.
"This is the first, large population-based study to link PBDEs with babies' birth outcomes," lead author Kim Harley, adjunct assistant professor and associate director of the Center for Environmental Research and Children's Health at the University of Berkeley, says in a statement. "A 4.1-ounce decrease in weight is a fairly significant finding."
Harley and colleagues point out that although the study found a decrease in birth weight overall, very few babies in the study were born weighing less than 5.5 pounds -- the clinical definition of low birth weight.
Low birth weight babies are more likely to experience social and cognitive delays in development.
"This was a very healthy population, and we didn't see many low birth weight babies. What we saw was a shift toward lighter babies among women with higher PBDE exposure rather than a dramatic increase in the number of low birth weight babies," Harley adds. "However, she points out that a 4.1 oz. shift could make a big difference for babies already at risk of being low birth weight, including low-income populations with poor access to prenatal care."