Children whose mothers lived near a busy highway while pregnant may be more likely to develop autism.
Researchers from the University of Southern California compared 300 children with autism to about 260 without.
Autism was more prevalent in kids when their mothers lived within 1,000 feet of a freeway while pregnant, particularly in the third trimester when fetal brains are developing quickly.
There is no known cause for autism, many experts believe it's often related to a complicated combination of genes and environmental factors.
Research into the highway connection is ongoing.