Feb. 12 2013

Prenatal folic acid supplements appear to reduce the risk for autistic spectrum disorders, according to a study in the Journal of the American Medical Association (JAMA).

The report in JAMA emerged from the Norwegian Mother and Child Cohort Study (MoBa) and its sub-study of autism, the Autism Birth Cohort (ABC) Study. This international collaboration (see list of members below) comprises the largest prospective birth cohort devoted to the investigation of gene-environment interactions and biomarker discovery for neuropsychiatric disorders.

A total of 85,176 MoBa babies—born from 2002-2008—and their parents participated in the study. Prenatal dietary habits were recorded, and families were regularly surveyed for 3-10 years to measure the development of autism spectrum disorders. A total of 270 cases of autism spectrum disorders were identified in the study population (114 autistic disorder; 56 Asperger syndrome; 100 atypical or unspecified autism; i.e., pervasive developmental disorder not otherwisespecified, PDD-NOS).

Mothers who took folic acid supplements in early pregnancy had a 40% reduced risk of having children with autistic disorder compared with mothers who did not take folic acid. The reduction in risk was observed in those who took folic acid during the time interval from 4 weeks before to 8 weeks after the start of pregnancy. Autistic disorder is the most severe form of autism spectrum disorders in children. No reduction in risk was observed for PDD-NOS. For Asperger syndrome, the number of children was too low to obtain sufficient statistical power in the analyses.