A recent study claims that women who take folic acid supplements before conception are at a lower risk of having an autistic child. In Association Between Maternal Use of Folic Acid Supplements and Risk of Autism Spectrum Disorders in Children the authors found that the odds of a child being autistic were 40% lower if the mother took prenatal folic acid supplements. The researchers used the Norwegian Mother and Child Cohort Study(MoBa). A couple of points need to be raised: the report focused on autistic disorder, not ASD’s in general. The number of individuals with Asperger syndrome or PDD-NOS were low, limiting the ability to detect differences. Given that limitation, they found no decreased risk for AS and PDD-NOS with pre conception folic acid supplementation.
Here is part of the abstract:
Results At the end of follow-up, 270 children in the study sample had been diagnosed with ASDs: 114 with autistic disorder, 56 with Asperger syndrome, and 100 with PDD-NOS. In children whose mothers took folic acid, 0.10% (64/61 042) had autistic disorder, compared with 0.21% (50/24 134) in those unexposed to folic acid. The adjusted OR for autistic disorder in children of folic acid users was 0.61 (95% CI, 0.41-0.90). No association was found with Asperger syndrome or PDD-NOS, but power was limited. Similar analyses for prenatal fish oil supplements showed no such association with autistic disorder, even though fish oil use was associated with the same maternal characteristics as folic acid use.
Conclusions and Relevance Use of prenatal folic acid supplements around the time of conception was associated with a lower risk of autistic disorder in the MoBa cohort. Although these findings cannot establish causality, they do support prenatal folic acid supplementation.
The overall prevalence is somewhat low at 0.1-0.2%, but recall that they are focusing on autistic disorder, not ASD’s in general (especially in the abstract). A 40% reduction in autism risk is quite large if real. How does that stack up against other studies? There was a study just last year in the U.S.: 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, which also found a 40% lower risk of autism with Folic acid supplementation