FRIDAY, Jan. 20, 2012 (HealthDay News) -- Children born to women who smoke during pregnancy are not at increased risk for autism, according to a new study.
Smoking during pregnancy has been considered a possible cause of autism in children due to known links between smoking and behavioral disorders and obstetric complications, but previous studies of a connection between smoking during pregnancy and autism have had mixed results.
In this study, researchers analyzed data from nearly 4,000 Swedish children with autism and a control group of 39,000 children without autism. The results showed that 19.8 percent of the children in the autism group and 18.4 percent of those in the control group had mothers who smoked during pregnancy.
The study was published online in December in the Journal of Autism and Developmental Disorders and will appear in a upcoming print issue.
"We found no evidence that maternal smoking during pregnancy increases the risk of autism spectrum disorders," study leader Brian Lee, an epidemiologist at the School of Public Health at Drexel University in Philadelphia, said in a university news release.
"Past studies that showed an association were most likely influenced by social and demographic factors such as income and occupation that have associations with both the likelihood of smoking and with the rate of autism spectrum disorders," he added.
Lee said the findings help reassure mothers who smoked during pregnancy that their behavior likely didn't cause their child's autism and "crosses off another suspect on the list of possible environmental risk factors for ASD (autism spectrum disorders)."
However, he reminded women that smoking during pregnancy is unhealthy for mothers and has known risks for their children.
The U.S. National Institute of Neurological Disorders and Stroke has more about autism.