The use of folic acid and multivitamin supplements by women before and during pregnancy was associated with a lower likelihood of autism spectrum disorder in children according to research published in JAMA Psychiatry.  However the authors warn that this finding needs to be interpreted with caution because other factors could explain it.

Maternal vitamin deficiency during pregnancy is associated in some studies with deficits in neural development in children.  To avoid neural tube defects in their children, pregnant mothers are routinely recommended to take folic acid during pregnancy but study findings about an association between maternal use of folic acid and multivitamin supplements and risk of autism spectrum disorder (ASD) in children have been inconsistent.

This is a case-control cohort study that compared children with an ASD outcome to children without that outcome to identify whether exposures to folic acid and multivitamin supplements during pregnancy may increase or protect against risk for ASD.  Researchers reviewed records of 45,300 Israeli children born between 2003-2007 and followed up to 2015.

Of the 45,300 children in the study (22,090 girls and 23,210 boys; mean age, 10.0 years at the end of follow-up), 572 (1.3%) received a diagnosis of ASD. Maternal exposure to folic acid and/or multivitamin supplements before pregnancy was associated with a lower likelihood of ASD in the offspring compared with no exposure before pregnancy (P < .001). Maternal exposure to folic acid and/or multivitamin supplements during pregnancy was associated with a lower likelihood of ASD in offspring compared with no exposure during pregnancy (P < .001). The results generally remained statistically significant across sensitivity analyses.

The authors conclude that maternal use of folic acid and multivitamin supplements before and during pregnancy appeared to be associated with a reduced risk for ASD in children compared with the children of mothers who did not use supplements.  However, the authors cannot rule out that the risk reduction is due to other causes.

Stephen Z. Levine, Ph.D., of the University of Haifa, Israel, and coauthors conducted the study.  They suggest that a reduced risk of ASD in children whose mothers used folic acid and multivitamin supplements before and during pregnancy could have important public health implications but more research is needed to examine this possible association.

This study was supported by grants from the National Institutes of Health, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Environmental Health Sciences, and National Institute of Neurological Disorders and Stroke.  Additional grants were received from the Beatrice and Samuel A. Seaver Foundation (Dr. Sandin is a Seaver Fellow), the Fredrik and Ingrid Thuring Foundation, and by the Swedish Society of Medicine.