Prenatal Supplements Can Decrease Autism Rates

Analysis by Dr. Joseph Mercola Fact Checked

folic acid iron reduces autism risk

Story at-a-glance

  • Research supports the use of prenatal vitamins rich in folic acid and iron before conception to reduce the risk of autism in families where autism has already been diagnosed in an older child
  • Although data reveals an increased familial risk for autism, no autism gene has been discovered; scientists acknowledge development of autism is multifactorial and may be influenced by both genetics and environmental exposures
  • Further, research indicates supplementation with 600 milligrams of the omega-3 fat docosahexaenoic acid (DHA) per day during pregnancy may reduce the risk of obesity-related high blood pressure during childhood
  • Children with autism have demonstrably different bacterial colonies in their gut, which may have a significant impact on their ability to withstand vaccinations. Improving the gut microbiome of children in the first 20 days of life may also help reduce their risk for autism


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

Prenatal care has drastically changed in the last 100 years. Up until 75 years ago, nearly 66 percent of U.S. women had a home birth with no painkillers. The practice of modern obstetrics included a trend toward hospital births. Much of the first issues in obstetrics was the debate over analgesics used during childbirth and the effort to find something safe for both the mother and the child.1

Nurses played an active role in starting prenatal care programs before hospital births became the norm and data demonstrated prenatal care reduced infant mortality. Routine evaluation for blood pressure, urine and weight were included in prenatal care visits. Since then, screenings have been added for other maternal risk factors and indicators of abnormal fetal development.2

By the 1980s prenatal care primarily focused on prompt treatment of complications rather than promotion and prevention.3 While the current pattern for prenatal visits usually begins in the first trimester, researchers are now investigating the effectiveness of preconception care.

Care before conception includes advising women on steps they may take to help prevent illness and promote health of mother and baby. One such study published in JAMA Psychiatry looked at the association of prenatal vitamins with the risk of autism in families who already had a child diagnosed with autism spectrum disorder (ASD).4

Autism and Genetics

Autism encompasses a broad range of conditions characterized by challenges with social skills, communication and repetitive behaviors. Autism is a spectrum disorder, meaning the symptoms can be classified in terms of their position on a scale.

According to Autism Speaks,5 there is not just one type of autism but many subtypes influenced by a combination of genetic and environmental factors. Each individual has a distinct set of strengths and challenges affecting how they learn, think and problem-solve.

In some cases, people with ASD require significant support, while others can live independently and hold high-functioning positions. Several factors are thought to influence the development of the condition, including gastrointestinal disorders.

In most children symptoms of ASD appear by age 2 or 3, although symptoms of associated developmental delays may appear even earlier. Since the 1970s, when researchers discovered pairs of identical twins often shared ASD, they have known the condition has a genetic component.6

Through years of investigation to find the genetic culprit, researchers have unearthed a variety of different genetic changes. Still, scientists agree that at this time there is no such thing as an autism gene. However, there are several genetic conditions highly associated with autism, including Fragile X and Retts syndrome. Boys appear to have a greater risk of developing autism than girls.

Scientists have also found that girls with autism have more DNA mutations than boys with the condition. These and other results suggest girls may somehow be more resistant to mutations and need a larger genetic change to exhibit symptoms.7

Prenatal Vitamins May Reduce Risk of Autism Spectrum Disorder

If one identical twin has autism, there's an 80 percent chance the other twin will as well. Fraternal twins have a 40 percent chance of sharing autism, which is close to the predisposition found in other studies for recurring siblings to demonstrate symptoms of ASD.

In one study, researchers enrolled 463 pregnant women and found a 24 percent familial recurrence risk for ASD.8 More recently, researchers followed 241 families and found 32.7 percent of children developed autism without prenatal vitamin intervention.9

Researchers wanted to know whether maternal use of prenatal vitamins might reduce the risk of autism in siblings of children who suffered ASD. In this sample of families, recruited at the MIND Institute from the University of California, Davis (UCD), younger siblings were born between December 1, 2006, and June 30, 2015.

Final clinical assessments of the children were completed within six months of their third birthday and moms reported use of prenatal vitamins during their pregnancy in telephone interviews. According to the researchers, while most mothers reported taking prenatal vitamins during the pregnancy, only 87 (36.1 percent) took prenatal vitamins in the six months prior to pregnancy.10

In this last group, only 14 percent of children were diagnosed with ASD, compared to 32 percent of children whose mothers did not take prenatal vitamins during preconception. Mothers who reported taking prenatal vitamins during the first month were also less likely to have children with ASD, compared to mothers who reported not taking prenatal vitamins at all.11

The researchers concluded prenatal vitamins during the first month may reduce ASD, but additional research is needed to confirm the results and to analyze the impact dosage has on the development of ASD. Dr. Pankhuree Vandana, child psychiatrist and medical director of the Autism Center at Nationwide Children's Hospital, who was not involved in the research, believes this was an important study.12

Children born to mothers taking prenatal vitamins scored higher in cognitive scores and had less severe symptoms if they were ultimately diagnosed with ASD. The reduction in risk for ASD seemed to be greater in moms whose prenatal vitamins had higher doses of iron and folic acid, which suggested there may be a partial dose effect.13

Consider Folate-Rich Foods or Folate Supplementation

One in every 59 children in the U.S. is diagnosed with one form of autism or another. According to the UCD researchers, siblings of children with the disorder are 13 times more likely to develop ASD than the general population.14 While the study results were based on prenatal vitamins containing folic acid, it's important to realize there is a significant difference between folate and folic acid.

Oftentimes these terms are used interchangeably and some argue they are essentially the same nutrient,15 but there is an important distinction. Folate is the term for the water-soluble B vitamin, B9. It is naturally found in foods as a tetrahydrofolate derivative that enters the metabolic cycle and is metabolized in the mucosa of your small intestine.16

Folic acid is an oxidized synthetic compound manufactured for dietary supplements and food fortification.17 It is initially metabolized in your liver and then enzymatically converted into its tetrahydrofolate form.

However, if you have low activity of the required enzyme in your liver, it can result in unnaturally high levels of unmetabolized folic acid in your circulation. This increased level has been associated with an increased prevalence of colon cancer18 and an increased risk of prostate cancer.19

In other words, getting your folate from natural food sources is much healthier than eating processed foods supplemented with folic acid (or taking a folic acid supplement).

Natural folate can be found in romaine lettuce, spinach, parsley, broccoli and cauliflower. The richest food sources are calf and chicken livers. If seeking supplementation, consider using folate products that list 5-methyltetrahydrofolate (5-MTHF) on the label, not folic acid.20

Omega-3 Prenatal Supplements and High Blood Pressure in Children

In another recent study,21 researchers evaluated the consumption of docosahexaenoic acid (DHA), a marine-based omega-3 fatty acid, during pregnancy and the relationship between intake and high blood pressure in children triggered by obesity.

Researchers from the University of Kansas undertook a clinical trial with women who had low-risk pregnancies. Half the group were assigned a daily prenatal supplement including 600 mg of DHA and the other half were given a placebo. The researchers' intent was to measure outcomes of the intervention in pregnancy and childhood development through age 6.22

In the placebo group, the data indicated an expected rise in blood pressure secondary to obesity, but a concurrent increase in blood pressure with obesity was not found in the group whose mothers took DHA. The difference in blood pressure increases was statistically significant.

Many prenatal supplements sold in the U.S. contain DHA but most have less than 600 mg. Nearly 20 percent of school-age children and young adults are obese according to the Centers for Disease Control and Prevention (CDC).23 Although the data tracked children up till age 6, the investigators hope the lower blood pressure may extend beyond childhood.

Co-author of the study John Colombo, Ph.D., from University of Kansas, states the research was aimed at pediatricians and mothers who wonder what to do prior to the birth to optimize health and behavioral outcomes. He went on to say:24

"The prenatal environment programs a fetus' metabolism for what to expect in the postnatal environment. Part of DHA's known effects may be in programming cardiac function that preserves normal blood pressure in the case of high postnatal weight gain."

Importance of Preconception and Prenatal Care

Having a healthy pregnancy is one of the best ways to promote healthy birth and a healthy childhood. Preconception and prenatal care improves the chances of a healthy pregnancy. If you're considering becoming pregnant, begin taking steps to promote a healthy pregnancy by increasing your daily intake of folate from natural foods or supplementing with 5-MTHF, and optimize your omega-3 level. Ideally, you'll want an omega-3 index above 8 percent.

Avoid smoking, drinking alcohol and using recreational drugs; reduce your prescription drugs to those only medically necessary and learn about your family and partner's medical history. It is also important to get any medical conditions under control and seek to attain a healthy weight.25

Once you suspect you may be pregnant, schedule a visit with your health care provider to start prenatal care. Your doctor will begin with a physical exam, weight check and urine sample.

Discussions about your health history, infectious diseases and your blood type will also be part of the examination. Regular prenatal care will reduce the risk of complications during pregnancy and birth and will create a good foundation for your child's health as he or she grows.

Protect Gut Health Before and After Birth

The diagnosis of ASD has skyrocketed over the past few decades, and while scientists and public health officials continue to argue about the reasons why it is happening, something is clearly very wrong. Just 30 years ago autism affected 1 in 10,000 children.26 Today, prevalence is as high as 1 in 50, according to some estimates.27

The Gut and Psychology Syndrome (GAPS)28 protocol is, in my view, among the most important treatment strategies to undertake, but there are also others. The GAPS nutritional protocol was created by Dr. Natasha Campbell-McBride,29 whose son was diagnosed with autism.

She understands there is an important connection between damaged gut flora in pregnant women and developmental problems in their children, especially autism. Establishing normal gut flora in the first 20 days or so of life plays an important role in the maturation of your baby's immune system.

Importantly, abnormal gut flora can compromise your baby's immune system, placing him or her at higher risk for vaccine reactions. According to Campbell-McBride, in children with GAPS, the toxicity originating from their gut travels through their bodies and into their brains. This continually challenges the nervous system and prevents it from performing normal functions and processing sensory information.

Other researchers are now starting to back up her findings. For example, one 2013 study30 confirmed children with autism have a distinctly different microbiome compared to healthy children. Notably, they had fewer healthy bacteria, such as Bifidobacterium. Children diagnosed with autism also had markedly higher levels of toxic volatile organic compounds (VOCs).

You can learn more about this in "GAPS Nutritional Program: How a Physician Cured Her Son's Autism," which includes my interview with Campbell-McBride. You can also find more information in my "No-Nonsense Guide to a Naturally Healthy Pregnancy and Baby."


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