Review and meta-analysis found that prenatal folic acid was associated with a 58% reduction in autism but had no effect on mental and motor development

Abstract

Aim: The impact of prenatal folic acid on children's neurodevelopment and the risk of autism spectrum disorder (ASD) remain unclear and this review and meta-analysis aimed to quantify any associations.

Methods: We systematically searched PubMed, Scopus and The Cochrane Library until June 2018 with no language restrictions. Standardised mean differences and odds ratio with 95% confidence intervals are used to describe any associations between folic acid and mental development, motor development and ASD.

Results: The search strategy identified 647 papers and 16 were finally included in the meta-analysis after the application of the exclusion criteria. These provided a total cohort size of 756 365 children aged 11 months to 15 years from 10 countries. The main finding was that prenatal use of folic acid was associated with a 58% reduction in the risk of ASD in children. We were surprised that better scores for mental development were associated with low prenatal exposure to folic acid.

Conclusion: Although the results should be interpreted with caution, they showed that routine prenatal supplements of folic acid were associated with significantly lower levels of ASD. Further studies are needed to reach a firm conclusion, given the multifactorial aetiology of neurodevelopment.

Keywords: Autism spectrum disorder; Folic acid; Mental development; Motor development; Prenatal supplements.