"A total of 22 original papers that examined the association between folic acid supplementation in human pregnancy and neurodevelopment/autism were identified after the screening, with 15 studies showing a beneficial effect of folic acid supplementation on neurodevelopment/autism, 6 studies showed no statistically significant difference, while one study showed a harmful effect in > 5 mg folic acid supplementation/day during pregnancy."
That rather long quote taken from the paper published by Yunfei Gao and colleagues  (open-access) opens today's post and provides a welcome [peer-reviewed] overview of where science is up to when it comes to the effects (or not) of pregnancy folic acid supplementation on 'risk' of offspring autism. I say 'where the science is up to' but at the same time note that the various searches of databases for material relevant to this topic/review was carried out up to the end of 2014. There have been other reports since that date including other reviews ...
Folic acid or folate in the context of autism has been a recurrent research theme down the years. Outside of the protective effects of pregnancy folate use with regards to reducing the risk of offspring neural tube defects (NTDs), the suggestion that pregnancy folic acid may confer a protective effect against offspring autism has been highlighted in several studies (see here).
Gao et al trawled the research literature and "included randomized controlled trials (RCTs), cohort studies, and case control studies that examined the association between folic acid supplementation during pregnancy and neurodevelopment/autism in the offspring children." As per that lengthy opening sentence from their paper, the authors found data that on the whole suggested that folate supplementation was protective rather than harmful when it came to offspring developmental outcomes. Given that most/many pregnant women are already taking folic acid during pregnancy to counter the risk of NTDs, this is good news indeed.
Without giving any undue weight to those studies that have perhaps not been so enthusiastic about the link between pregnancy folate use and offspring autism risk (see here) I do think there are words of caution in this area too. We're still for example, waiting for research to be published that was raised at this years IMFAR event in relation to folic acid and autism (see here). Indeed, in my discussion of that so-far-unpublished work, I mentioned that the genetics of folic acid metabolism also needs to be further inspected when it comes to autism (see here) and that screening for particular issues linked to folate might be something to consider for people on the autism spectrum and their significant others (see here). Both these areas are potentially relevant to that recent chatter on how folinic acid might be useful for some aspects of some autism (see here).
"Large scale RCTs with validated diagnosis and high follow up rate are needed in order to produce robust evidence regarding the effects of folic acid supplementation in pregnancy on fetal neurodevelopment" conclude the authors. Yes, we need more investigation of this area - including what effect certain medicines used during pregnancy might have had on folate levels - but for now, the data seems to side with a protective effect of folate supplementation in pregnancy when it comes to offspring risk of autism or related neurodevelopmental issues.
 Gao Y. et al. New Perspective on Impact of Folic Acid Supplementation during Pregnancy on Neurodevelopment/Autism in the Offspring Children – A Systematic Review. PLoS ONE. 2016; 11(11): e0165626.
 DeVilbiss EA. et al. Maternal folate status as a risk factor for autism spectrum disorders: a review of existing evidence. Br J Nutr. 2015 Sep 14;114(5):663-72.
Gao Y, Sheng C, Xie RH, Sun W, Asztalos E, Moddemann D, Zwaigenbaum L, Walker M, & Wen SW (2016). New Perspective on Impact of Folic Acid Supplementation during Pregnancy on Neurodevelopment/Autism in the Offspring Children - A Systematic Review. PloS one, 11 (11) PMID: 27875541