That Study Making Its Way Around the Web Doesn't Say That Prenatal Vitamins Cause Autism

Illustration for article titled That Study Making Its Way Around the Web Doesnt Say That Prenatal Vitamins Cause Autism

Last week, researchers at Johns Hopkins released a study that analyzed the relationship between levels of folate and vitamin B12 in a mother’s system and their children’s risk of autism. The study found that women with heightened levels of both folate and vitamin B12 were 17.6 times more likely to have children diagnosed with an autism spectrum disorder.


From the findings, a number of news sources stoked anxiety over prenatal vitamins, a primary source of folate for pregnant women. The Cut described the findings as “upsetting” and “alarming,” particularly since folate deficiency is, as the Hopkins study notes, “a well-recognized risk factor for neural tubal defects.” Yet despite the findings, the Los Angeles Times reports that removing prenatal vitamins from a pregnant woman’s daily routine “is actually contrary to the study’s findings.”

The study wasn’t the first of its kind; as its authors note, there’s conflicting evidence about the role that folate and vitamin B12 play in the possible development of autism:

While some studies have suggested that mothers’ periconceptional multivitamin use, dietary folic acid intake and/or folic acid supplementation are associated with a decreased risk of ASD in their children, others have suggested the opposite effect.


But the previous studies have all relied on maternal self-report of vitamin intake. This latest study analyzed data from 1,391 mothers and their children who participated in the Boston Birth Cohort, a research project that dedicated to understanding the root causes of developmental disorders. Researchers tracked the pairs over the course of 15 years. The LA Times reports:

“All of the mothers took surveys about their use of prenatal vitamins and other supplements throughout their pregnancies. The women also gave blood samples within three days of giving birth, allowing researchers to measure levels of prenatal vitamins in their systems at the end of their pregnancies.

Medical records showed that 107 of the 1,391 children were diagnosed with an autism spectrum disorder. But the risk of a diagnosis was not spread evenly among all mother-child pairs.”

Rather, the study found first:

“Maternal multivitamin supplement of 3-5 times/week was associated with significantly lower risk of ASD [Autism Spectrum Disorders] in offspring across all trimesters.”


And secondly:

“When maternal plasma folate and vitamin B12 levels were analyzed as exposure variables, high levels of maternal vitamin B12 were associated with significantly increased risk of ASD. High maternal folate levels were also associated with increased risk of ASD. The risk was greatest for those children whose mothers had both high plasma folate and vitamin B12.”


Essentially, very high levels of both folate and vitamin B12 led to an increased risk of autism, not simply folate as some have reported. Those findings led some to the conclusion that prenatal vitamins can lead to over supplementation, thus creating autism risks. But again, that’s not exactly what the Hopkins study found.

Among the 1,391 women in the study, 95 had an excessive amount of B12 in the system; among those women, 15 had children on the autism spectrum, an increased risk of three times the normal variable. Another group of 140 mothers had an excess of folate; among those women, 16 had children on the spectrum, roughly double the norm. Again, the women most at risk had high levels of both folate and vitamin B12, not simply folate.


Beyond those findings, the study also found that mothers in the “urban low-income minority birth cohort” were more at risk than their middle-class, white counterparts. Again, the LA Times notes:

It’s not clear why some of the women in the study – an “inner city, minority” population that is 65% African American and 25% Latina – had such high levels of folate and B12. It’s possible that they overdid it with their supplements, or that their bodies naturally absorb more of these vitamins or metabolize them more slowly...


Folate is an important essential vitamin and it’s particularly important in cell division and DNA construction. Pregnant women with folate deficiencies are far more likely to have children with spina bifida or other neural tube defects. That’s why the FDA requires that it’s added to bread and other grains. It’s not the enemy and neither are prenatal vitamins.

The Hopkins team themselves reiterated that their findings only led them to conclude that they need to do more research, particularly since excessive levels of folate and B12 seem to have more of an impact on women of color. “Maternal vitamin supplementation was protective,” against autism spectrum disorders, the authors told the LA Times. But, like practically everything when you’re pregnant, don’t overdo it.


Image via AP.

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I read that breathing air causes autism.