Mothers exposed to household or agricultural pesticides immediately before and during their pregnancies have a higher risk of having a child with autism spectrum disorder (ASD).  However, a recent study from California indicates that taking high-dose folic acid cuts this risk in half, as compared to women who received lower doses of folic acid.  In this study, a high dose of folic acid was defined as ?800 ?g, the amount typically found in prenatal vitamins.  The findings of this study is summarized here.  

These findings parallel findings from studies in women who are at lower risk of having a child with ASD (i.e., women who were not exposed to pesticide).  In this study, daily folic acid intake of ?600 ?g during the first trimester of pregnancy was associated with reduced ASD risk (adjusted OR: 0.62), and the risk estimates decreased with increasing intake of folic acid.

We have long known that supplemental folic acid is preventative against birth defects, particularly neural tube defects.  Importantly, the timing for the benefits of folic acid occur very early in pregnancy; thus, it is extremely important to emphasize use of supplemental folic acid even before conception, as many pregnancies are unplanned, and some women do not even realize they are pregnant before this window of opportunity to take folic acid has already passed.

The US Preventive Services Task Force (USPSTF) unequivocally recommends that ALL WOMEN who are either planning or capable of pregnancy take a DAILY SUPPLEMENT containing 0.4 TO 0.8 mg (400-800 µg) of folic acid.  

Ruta Nonacs, MD PhD


Pregnant moms who take folic acid cut autism risk from pesticides (Reuters)

R.J. Schmidt, V. Kogan, J.F. Shelton, L. Delwiche, R.L. Hansen, S. Ozonoff, C.C. Ma, E.C. McCanlies, D.H. Bennett, I. Hertz-Picciotto, D.J. Tancredi, H.E. Volk. 2017. Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder. Environ Health Perspect, 2017, 125(9).  DOI:10.1289/EHP604

J. Schmidt, D. J. Tancredi, S. Ozonoff, R. L. Hansen, J. Hartiala, H. Allayee, L. C. Schmidt, F. Tassone, I. Hertz-Picciotto. Maternal periconceptional folic acid intake and risk of autism spectrum disorders and developmental delay in the CHARGE (CHildhood Autism Risks from Genetics and Environment) case-control study. American Journal of Clinical Nutrition, 2012.