Prenatal vitamins during pregnancy reduce the risk of autism spectrum disorders

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If you are a regular reader of this blog, you know I’m not exactly a fan of vitamin supplements. They are expensive, and they don’t do what people want to believe they do. They do not reduce the risk of any cancer. They do not improve bone health. But I always forget to mention an important exception – prenatal vitamins and supplements that are well known to improve pregnancy outcomes.

And now it’s time for me correct this egregious oversight on the part of the feathered dinosaur’s body of work on supplements. Just to be clear, I always state an important caveat on my dismissing the usefulness of vitamins and supplements – those individuals with chronic disease or malnutrition may require supplements. For example, if you never touch a fruit or vegetable, you will probably need vitamin C to prevent scurvy. No, I didn’t say that vitamin C will prevent cancer, but it will prevent one disease.

Recently, a top peer-reviewed journal has published an article where the researchers showed that there was a lower risk of autism spectrum disorders in children of mothers who took prenatal vitamins. And I can write about one area of healthcare where some vitamins and supplements do have some value. This is more evidence that there are numerous issues that may lead to autism spectrum disorders – and it’s not vaccines.

Prenatal vitamins primer

There is some variety of what constitutes proper prenatal vitamins or supplements. Mostly, supplements attempt to safely increase or decrease (yes, if necessary) nutrients that may protect the mother and developing fetus. There is a boatload of science that supports what helps and harms the baby.

The list below probably constitutes a consensus on what prenatal vitamins should include:

  • Calcium – necessary for skeletal development
  • Iron – necessary for hemoglobin in red blood cells
  • Folic acid or folate (see Notes 1 and 2) – Folic acid, which is a B vitamin occasionally called B9, is critical during fetal development because it can prevent some major birth neural tube defects like anencephaly and spina bifida. It is one of the most important constituents of prenatal vitamins.
  • Vitamin D – necessary for the development of several organ systems
  • DHA or docosahexaenoic acid – it is a form of omega-3 fatty acids that may be important for fetal development of the fetal brain and nervous system.
  • Vitamin A – high levels of vitamin A may lead to congenital development issues with the developing fetus, so most prenatal vitamins have reduced amounts of the vitamin.

These prenatal vitamins are all critically important to the development of the fetus, reducing the risk of man congenital birth defects and other issues. Furthermore, the mother may also become deficient in these vitamins as she is sharing some of these vitamins with her developing fetus.

Prenatal vitamins and autism spectrum disorder

So, let’s get to the paper which is the reason for this blog post. It was written by Stephen Z Levine, Ph.D., et al. and published in January 2018 in JAMA Psychiatry. Dr. Levine is a researcher at the Department of Community Mental Health, University of Haifa, Haifa, Israel.

Researchers have been interested in finding any link between maternal vitamin deficiencies during pregnancy and neurodevelopment. Of course, the association between folic acid supplementation and neural tube defects has been known for decades. However, support for hypotheses about the relationship between these prenatal vitamins and autism spectrum disorder (ASD) have been inconsistent.

In the DSM-5, ASD is as a range of conditions characterized as neurodevelopmental disorders. Individuals who have been diagnosed with ASD present with two groups of symptoms – problems in social development, communication and interaction, and, repetitive patterns of behavior, interests, and activities. At this time, there are no known causes or “cure.”

Dr. Levine was attempting to answer the question whether “maternal folic acid and/or multivitamin supplement use before and/or during pregnancy increase(s) the risk of autism spectrum disorder in offspring?”

To answer this question, the investigators used a case-control cohort study that followed 45,300 Israeli children born between 2003-2007 with evaluations extending to 2015. The University of Haifa researchers questioned mothers about their use of folic acid and other prenatal vitamins during pregnancy. Then they determine whether their child received an ASD diagnosis.

The researchers found that use of these supplements during pregnancy appeared to be correlated with a statistically significant 61% reduced risk for ASD in children compared to a group that did not use these supplements.

Although there appears to be a correlation, and we have some indication of biological plausibility that these vitamins are linked to neurodevelopment, the study design does not provide us with robust evidence of causality. A case-control cohort epidemiological study is observational where children who had an ASD outcome were compared to those who did not. It was not powered to examine if there were other factors that might have been contributed to this result.

However, this type of study is a powerful method to uncover a correlation between a medical intervention and an outcome. Larger, more powerful epidemiological studies are necessary to confirm a causal relationship between prenatal vitamins and ASD.

If this study is confirmed, then it might result in important public health implications. The CDC, if they’re allowed to use the dirty word fetus, might have to increase their efforts to increase the use of vitamin supplements during pregnancy to reduce the risk of autism spectrum disorder.

This is a strong study that does have some weakness. But based on these initial results, I’d certainly be pushing prenatal vitamins if my significant other was pregnant. Yes, you heard it here, I’m advocating vitamin supplements, although for a very narrow purpose.


  1. There are numerous comments on the internet that somehow there is a magical difference between folic acid and folate (which are sometimes called vitamin B9). Despite the pseudoscience surrounding using one or the other, they are chemically equivalent. Folate is the term that is used to name the many different forms of the vitamin – this includes tetrahydrofolic acid (the activated form of the vitamin), methyltetrahydrofolate, methenyltetrahydrofolate, and folinic acid. However, these are the just different names for the same active ingredient.

    Organic chemistry naming conventions call the complete compound X-ic acid (like folic acid). It is called X-ate (like folate) when it loses a proton. The vitamin shifts back and forth between the folic acid and folate forms based on the acidity of the solution. This is an instantaneous shift between forms, and it has no practical difference with respect to physiology. Folate is just folic acid in a neutral or basic solution.

    To make a claim that folic acid is better than folate or vice versa is rather ridiculous, based on naming conventions of organic chemistry. However, if someone can provide me with peer-reviewed articles in high-quality journals that establish a substantial difference between the two forms of folic acid, I will graciously change my understanding of every amino acid, all of which exist freely in either -ic or -ate forms.

  2. Using an incredible level of mental gymnastics, that resemble the convoluted logic of climate change deniers, some anti-vaccine activists are claiming that there is some complicated connection between vaccines, autism, and the MTHFR gene. There is a very rare genetic mutation which causes MTHFR, an enzyme, to become deficient, and folic acid supplementation may be necessary to treat the disease. I have disputed any link between MTHFR mutations and vaccine adverse effects, but the internet trope persists. I guess folic acid, MTHFR, vaccines, and autism are all interlinked. Stay tuned, this small note may become a full article.


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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!