December 18, 2014
Science Daily/Harvard School of Public Health
Women exposed to high levels of fine particulate matter specifically during pregnancy -- particularly during the third trimester -- may face up to twice the risk of having a child with autism than mothers living in areas with low particulate matter, according to a study. The greater the exposure, the greater the risk, researchers found. It was the first US-wide study exploring the link between airborne particulate matter and autism.
"Our data add additional important support to the hypothesis that maternal exposure to air pollution contributes to the risk of autism spectrum disorders," said Marc Weisskopf, associate professor of environmental and occupational epidemiology and senior author of the study. "The specificity of our findings for the pregnancy period, and third trimester in particular, rules out many other possible explanations for these findings."
The researchers explored the association between autism and exposure to PM2.5 before, during, and after pregnancy. They also calculated exposure to PM2.5 during each pregnancy trimester.
Exposure to PM2.5 was significantly associated with autism during pregnancy, but not before or after, the study found. And during the pregnancy, the third trimester specifically was significantly associated with an increased risk. Little association was found between air pollution from larger-sized particles (PM10-2.5) and autism.
"The evidence base for a role for maternal exposure to air pollution increasing the risk of autism spectrum disorders is becoming quite strong," said Weisskopf. "This not only gives us important insight as we continue to pursue the origins of autism spectrum disorders, but as a modifiable exposure, opens the door to thinking about possible preventative measures."