Can autism risk be reduced with prenatal vitamins? Sounds too simple.

A new study on the potential causes and prevention of autism has been released, and this one may result in a rush to the vitamin store. Among 700 families in Northern California, women who reported that they had not taken prenatal vitamins immediately before and during the first month of pregnancy were twice as likely to have a child with autism, including autism spectrum disorders, according to a team of epidemiologists from the University of California-Davis Medical Investigation of Neurodevelopmental Disorders Institute. Published in the journal Epidemiology, the researchers found that the mothers of the 288 toddlers with autism and the 141 with ASD, as compared to the mothers of the 278 children with normal development, were one-half as likely to have taken prenatal vitamins immediately before or during the first month of their pregnancies.

These families all participated in the Childhood Autism Risk from Genetics and the Environment study. The results revealed that there was no effect on the incidence of autism if women waited until the second month of pregnancy to begin taking prenatal vitamins.

As promising as these findings may sound, ACSH's Dr. Gilbert Ross is skeptical of the study authors’ conclusions. First of all, he says, “the researchers may very well be confusing cause and effect. The cohort of women who did not take prenatal vitamins may be a self-selected group, in that they likely have other, less conscientious health-related behavior.” While he encourages all expectant mothers to take prenatal vitamins, he isn’t about to declare them a means of preventing autism, “although it would be a wonderful advance if better, prospective studies can confirm this one.”