Folic Acid During Pregnancy – Too Much of a Good Thing?

Recently I was sitting at a dinner with some friends discussing all the rules of pregnancy and how some are silly, some are crucial, and some important things are totally overlooked.  It was brought up that a recent study has suggested that too much folic acid during pregnancy may contribute to autism.  I was shocked; I had only ever heard  how important folic acid is in the prevention of birth defects like spina bifida.  In fact, it’s recommended that your intake be 400 mcg of folic acid per day even before you become pregnant (CDC).

This new study is all over the news and being cited by many news agencies.  But is it, like so many medical studies, being sensationalized?  Is this the next Vaccination controversy?

The study followed 1,391 babies who were born at Boston University Medical Center from 1998-2013.  Of these children, around 100 were diagnosed with autism.  The researchers at Johns Hopkins Bloomberg School of Public Health analyzed the levels of Folic Acid and Vitamin B12 in the mother’s blood after delivery. They found that women with more than four times the recommended amount of folate had double the risk of their child developing autism, high B12 levels tripled the risk, and high levels of both increased the risk by 17.6 times. (  This study was only presented on May 13th, and has yet to be peer reviewed, so findings should be taken with a grain of salt.

My questions when I read this are as follows, and the answers I found (or couldn’t find) are below.

  • How uncommon is it throughout the population to have extremely high levels of folic acid after childbirth?
    • “We don’t at a population level know what the average amount of folic acid in a pregnant woman might be,” – Dr. Cynthia Gyamfi-Bannerman, associate professor of obstetrics and gynecology at Columbia University Medical Center Maternal-Fetal Medicine.
    • Briefly: They don’t know.


  • What caused extremely high levels of folic acid in these women?
    • “A large majority of the mothers in the study reported having taken multivitamins – which would include folic acid and vitamin B12 – throughout pregnancy. But the researchers say they don’t know exactly why some of the women had such high levels in their blood. It could be that they consumed too many folic acid-fortified foods or took too many supplements. Or, they say, it could be that some women are genetically predisposed to absorbing greater quantities of folate or metabolizing it slower, leading to the excess. Or it could be a combination of the two.” –
    • Briefly: They don’t know.


  • What is the recommended amount of folic acid during pregnancy?
    • According to Women able to get pregnant need 400 to 800 mcg or micrograms of folic acid every day, even if they are not planning to get pregnant. (This is the same as 0.4 to 0.8 mg or milligrams.) That way, if they do become pregnant, their babies will be less likely to have birth defects. Talk with your doctor about how much folic acid you need if:
      • You are pregnant or are planning to become pregnant. Pregnant women need 400 to 800 mcg of folic acid in the very early stages of pregnancy often before they know that they are pregnant. A pregnant woman should keep taking folic acid throughout pregnancy. Women should discuss their folic acid needs with their doctors. Some doctors prescribe prenatal vitamins that contain higher amounts of folic acid.
      • You are breastfeeding. Breastfeeding women need 500 mcg. Some doctors suggest that breastfeeding women keep taking their prenatal vitamins to be sure they are getting plenty of folic acid while they are breastfeeding and should they become pregnant again.
      • You had a baby with a birth defect of the brain or spine and want to get pregnant again. Your doctor may give you a prescription for 4,000 mcg of folic acid. That is 10 times the normal dose. Taking this high dose of folic acid can lower the risk of having another baby with these birth defects.
      • You have a family member with spina bifida. Your doctor may give you a prescription for 4,000 mcg folic acid.
      • You have spina bifida and want to get pregnant.
    • Breifly: It depends.  I’d recommend discussing with your OB what applies to you specifically.


  • How can a pregnant woman ensure that she’s in the recommended range for folate or Vitamin B12 while eating healthfully?
    • Folic acid is naturally found in many healthy foods like leafy greens, beans, citrus, and whole grains.  It’s also added to many “enriched” foods like flour, bread, cereal, pasta, & white rice.  For these you can check the label to see how much folate is in your serving.
    • A typical prenatal vitimin has 800 mcg of folic acid
    • But I don’t know about you, but I certainly don’t go around adding up my folate from all these different things I eat.  To me, it seems like the best method would be to be mindful of what you’re eating for a day or two to see where your natural level of folic acid consumption is, and then calculate what you’re getting in addition to supplements.  Or just admit that it’s really really hard to know how much you’re getting each day, and do your best not to take 5 prenatal vitamins at a time.
    • Briefly: There’s no exact science.


  • So how should this change what I’m doing or planning to do while pregnant?
    • “Vitamins are still important during pregnancy. Researchers found that taking multivitamins three to five times a week during pregnancy was associated with a lower risk of autism.The American Congress of Obstetricians and Gynecologists recommends that pregnant women get at least 600 micrograms of folic acid daily from all sources. “Staying within the current parameters would be both prudent and important until we have more information to confirm these findings,” said Gyamfi-Bannerman.” –
    • I actually didn’t realize how important folic acid is until doing this research, and especially how important it is to take a prenatal even before a woman starts trying to get pregnant.  I also acknowledge that this is a study that hasn’t had every idea or question completely flushed out.  So my 2 cents is to continue taking recommended dosages of folic acid, but be on the lookout for a  change in the recommendations and stay informed.
    • Briefly: Don’t do anything rash.


  • And PS – is Folate the same as Folic Acid?
    • All the articles I read basically used them interchangeably, so I did too.
    • Folate is a general term for a group of water soluble b-vitamins, and is also known as B9. Folic acid refers to the oxidized synthetic compound used in dietary supplements and food fortification, whereas folate refers to the various tetrahydrofolate derivatives naturally found in food. (Source)
    • Briefly: Close enough for me.

I hope that helps, although for me, in some ways it raised more questions than answers. I’ll definitely be keeping an eye out for more information on this, and be sure to share what I find.

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