By Dennis Thompson
"Reduced risk of [autism] in offspring is a consideration for public health policy that may be realized by extended use of folic acid and multivitamin supplements during pregnancy," the researchers concluded in the report.
The international team of scientists, led by Stephen Levine from the University of Haifa in Israel, gathered data on tens of thousands of children born in Israel between 2003 and 2007, and followed their progress until 2015.
The team also gathered prescription data, to see whether the kids' mothers had been prescribed folic acid or multivitamin supplements either prior to or during pregnancy.
Women who took supplements prior to pregnancy were 61 percent less likely to have a child diagnosed with autism, compared with moms who didn't take supplements, the researchers found.
In addition, taking supplements during pregnancy was linked to a 73 percent reduced risk of an autism diagnosis, the findings showed.
The overall risk of autism remained low, with only 1.3 percent of the children in the study receiving a diagnosis.
But these study results suggest that taking folic acid and multivitamins could be a way to protect babies against the development of autism, said Tom Frazier, chief science officer for Autism Speaks, a group that promotes advocacy and support for individuals with autism and their families.
Women already are urged to take folic acid during pregnancy to prevent birth defects of the spinal cord and the brain, Frazier said. Multivitamins also are recommended to help cover any nutritional gaps in an expecting mom's diet.
"The study suggests this is not a trivial recommendation. This is something that people really should pay attention to," Frazier said. "The reduction in risk isn't huge, but it isn't small either."
Folic acid plays an essential role in fetal neural development, and a lack of the vitamin could possibly set the stage for later onset of autism, Frazier said. He's not sure how the protective effect of multivitamins might work.
But the study cannot prove a direct cause-and-effect link between supplements and autism due to its design, and suffers from some major limitations, said Dr. Ruth Milanaik. She is director of the neonatal neurodevelopmental follow-up program at Cohen Children's Medical Center, in New Hyde Park, N.Y.
For example, the study could not clearly determine which women actually took their supplements, Milanaik argued.
Prescription records can't show whether women follow through and take their supplements, she said. Supplements also are available over-the-counter, and some of the moms could have purchased and taken them without waiting for a prescription.
"I don't have a problem with saying folic acid is good for pregnant women. You should not only take folic acid during pregnancy, you should also take folic acid before pregnancy," Milanaik said. "But this study does not show that [not taking supplements] is a cause of autism in any way, shape or form."
The study was published online Jan. 3 in the journal JAMA Psychiatry.