U.S. expert Halladay had advice for mothers-to-be.
"Pregnant women should follow the direction of their doctor or health care provider to maintain a healthy pregnancy," Halladay said. "This includes avoiding illness and infection."
While the study found a possible association between maternal infection and autism, it did not prove a cause-and-effect relationship.
For more on autism, visit the U.S. Centers for Disease Control and Prevention.
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