According to a Norwegian biobank study “Association of Folic Acid Supplementation During Pregnancy With the Risk of Autistic Traits in Children Exposed to Antiepileptic Drugs In Utero” [1]:
Children exposed to antiepileptic drugs in utero had a significantly lower risk of autistic traits if the mother used periconceptional folic acid supplements.
The population-based, prospective Norwegian Mother and Child Cohort Study approached Norwegian-speaking women attending routine ultrasonographic examinations from June 1999 through December 31, 2008. The study included 104,946 children.
In the 335 children exposed to antiepileptic drugs, the risk for autistic traits was significantly higher at 18 months of age and 36 months of age when their mothers had not used folic acid supplements compared with children of mothers who had used supplements.
[The study concluded that] fertile women using AEDs should take folic acid supplements continuously.