Periconceptual folate and autismBMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f900 (Published 13 February 2013) Cite this as: BMJ 2013;346:f900
Researchers from Norway have found a link between periconceptual folic acid supplements for women and a lower risk of autistic disorder in their young children. In a large cohort study, the risk of autistic disorder was 0.1% (64/61 042) in children of women who took such supplements and 0.21% (50/24 134) in children of women who took none. After multiple adjustments, the researchers report a significant reduction in odds associated with supplements taken at any time between four weeks before the start of pregnancy and eight weeks after (odds ratio 0.61, 95% CI 0.41 to 0.9).
Autistic disorder is the most severe of the autism spectrum disorders, say the researchers. They couldn’t confirm or rule out a link between periconceptual folic acid and other disorders on the spectrum, including Asperger’s syndrome. They tracked more than 85 000 children to a mean age of 6 years (range 3-10); 270 were diagnosed as having autism spectrum disorders during follow-up.
Could folic acid supplements help prevent autism? It’s too early to say, but these findings are encouraging, says a linked editorial (p 611). Secondary analyses found no association between autistic disorder and folic acid taken in mid-pregnancy, or between autistic disorder and fish oil supplements. Both argue against unmeasured confounding. Still, confirmation in other populations will be important. Flour is not fortified with folic acid in Norway, and the fact that the incidence of autism spectrum disorder has gone up in the US since fortification was introduced in 1998 is at odds with these findings, says the editorial.
Cite this as: BMJ 2013;346:f900