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Some data would have given weight to BMJ’s recap of multivitamins and autism study


3 Star

Multivitamins in pregnancy may be linked to lower autism risk in children

Our Review Summary

This BMJ news release suggests that a new study found a correlation between multivitamin use and reduced incidence of autism spectrum disorder (ASD). We commend the release for noting that the study findings show a correlation, not causation, and for making a call for more research. However, the largest drawback of the release is that it doesn’t provide any actual data from the study.

The release did call out some limitations of the research but would have been even stronger had it mentioned some very obvious differences between the group of mothers-to-be that took multivitamins and the expectant mothers who did not take supplements. The multivitamin group is more educated, in a higher socioeconomic group, has fewer smokers, are of more normal weight, more were born in Sweden and more were experiencing their first pregnancy. The presence of a higher percentage of women with overweight in the no vitamin group suggests that there are other nutritional factors that are unknown and may influence or increase the risk of having a child with ASD.


Why This Matters

Environmental factors in autism spectrum disorder are an area of active research as the prevalence of diagnosis has doubled since the year 2000. (Genetic influences are also actively studied.) Because these disorders are developmental in nature, prenatal influences are of particular interest. Ideally, continued research on nutritional influences might someday lead to advice for pregnant women to reduce the chances of having a child with ASD.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The news release did not mention costs of vitamin supplements.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The news release did not describe the size of the benefit, saying only that multivitamin use “was associated with a lower likelihood of child ASD with intellectual disability.” How much of a lower likelihood? And what are the absolute numbers? We would like to know how many of the 273,107 mother-child pairs used vitamins and how many children were diagnosed with ASD in the vitamin-taking moms and the moms who didn’t take vitamins.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

No mention of potential harms — or lack of harms, if that’s the case — from taking multivitamins or extra iron were mentioned in the release.

Does the news release seem to grasp the quality of the evidence?


The news release does a good job at defusing any presumption of cause-and-effect with this second paragraph: “The researchers stress that their findings cannot establish cause and effect, but say they raise questions about a possible association that warrant further investigation.”

The release also discusses strengths (large sample size) and limitations (presence of confounding factors and uncertainty about dosing and timing of vitamins) of the study.

However, the release omits any actual data, which we already pointed out in the Benefits section.

Does the news release commit disease-mongering?


The news release does not engage in disease-mongering. Autism spectrum disorders are simply described.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

The news release makes no mention of either funding sources or potential conflicts of interest involving the study authors. This information is plainly provided in the journal article’s footnotes which  lists the government funding sources and notes that “Researchers were independent from funders.”

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

The news release does not discuss that pregnant woman might achieve recommended vitamin intake via the food they eat.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Applicable

The news release doesn’t mention availability of multivitamins, but we concede that supplements are as widely available as are drug stores.

Does the news release establish the true novelty of the approach?


The news release informs readers that previous work on maternal nutrition and ASD have been inconsistent and that this study used different and multiple analyses to assess the link.

Total Score: 4 of 9 Satisfactory


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