Vitamin supplements used before or during pregnancy associated with risk of autism spectrum disorder

Bottom Line: 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 but this finding needs to be interpreted with caution because other factors could explain it.
Why The Research Is Interesting: 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.
Who and When: 45,300 Israeli children born between 2003-2007 and followed up to 2015
What (Study Measures): Maternal use of folic acid and multivitamin supplements before and during pregnancy (exposure); ASD (outcome). The association between maternal use of supplements and the likelihood of ASD in children was reported as a statistical measure known as relative risk (a relative risk less than 1 suggests less risk).
How (Study Design): This is a case-control cohort study, which is a type of observational epidemiologic study where children with an outcome (ASD) were compared to children without that outcome to identify exposures (maternal use of folic acid and multivitamin supplements) that may increase or protect against risk for ASD. Because researchers are not intervening for purposes of the study, they cannot control natural differences that could explain the study findings.
Results: 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.
Study Limitations: The authors cannot rule out that the risk reduction is due to other causes.
Study Conclusions: 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.