Vitamin D3 and Pregnancy

We’ve touched on vitamin D3 and how it impacts a pregnant woman’s mental health and over all resistance to sicknesses like the flu in previous blog posts.

I just found something that might end up putting Vitamin D3 right up there in importance with folic acid in the prenatal vitamin department. Of course, vitamin D3 isn’t actually a vitamin at all, and it’s best utilized by the body when it comes from a chemical reaction set off between the skin and the sun. (Vitamin D’s metabolic product is actually a hormone that is the key that unlocks binding sites on the human genome.) BUT… it’s certainly something that works well when supplemented and that’s a huge relief, because the human genome has more than 2700 binding sites for this hormone and those binding sites are near genes involved in virtually all known major diseases.  And specifically, it may be a relief to us in the Everything Birth community that it can be supplemented, because the “something that I found” is a pretty impressive study that stressed the importance of optimal vitamin D levels during pregnancy on fetal health.

“During pregnancy, higher maternal circulating concentrations of 25-hydroxyvitamin D3 correlates with improved mental and psychomotor development in infants, according to a study published online Sept. 17 in Pediatrics.” (source)

Here’s a link to the abstract from the prestigious journal Pediatrics. It was a Spanish population-based cohort study  using 1820 mother-infant pairs. So, it wasn’t a tiny study or anything.  It found that a higher level of Vitamin D3 in pregnant women’s body had a direct effect on positive mental and psycho-motor development in the infants born from them.

The Problem with the RDA of Vitamin D.

So many people look at the RDA on supplements and think that if they take a vitamin that has 100% of the RDA, they are golden.  As we learn more and more, we are consistently shown that RDA is basically, the bare minimum of what we need.  I say that as a general rule from my own non-medical understanding, though, if you look into RDAs you will most assuredly find this to be true as well. In this particular case, the better results came from babies born of women who had vitamin d3 levels which were greater than 30 ng/mL.

Please don’t apply this specific conversion to any other medication; it may not be applicable:

It’s super important to note that even this minimal amount that is recommended is under the pretense that pregnant women also get a minimal amount of sunlight. Not a lot, but at least some. Some of us much further from the equator simply don’t get even a minimal amount of sunlight.  Plus this amount is an average of our general poulation and it fares even worse for dark-skinned women who require much more sun to get the same level of vitamin D.

So, pregnant women getting about 600 IUs a day, with a minimal amount of sunlight, are expected to have levels at about 30 ng/mL.

That is what is considered not deficient.

This study says that women have to be OVER that level to see the improved mental and psycho-motor development. So, essentially, this study says that for the benefits to be seen women need to get MORE vitamin D than what the RDA suggests.

The Problem With Prenatal Vitamins

Many vitamin manufacturers suggest that the RDA is more like 400IUs because they still base it on the RDAs from before they were changed in 2010. This means that even a typical prenatal vitamin could be claiming to provide everything a pregnant mother could need, but essentially falling quite short. Even the very popular One-A-Day brand of prenatal vitamins considers 400IU to be 100% of what a pregnant woman needs. See the clip I got straight from their own site:


Keep in mind, the American Pregnancy Association says that you should never exceed the RDA of any substance without talking to your doctor about it. So, I think it’s time to talk to a doctor about it, don’t you?

Double Check Your Doctor’s Knowledge of Vitamin D

Chances are really good that any given pregnant woman in America does not have optimal vitamin D levels.  It’s considered to be an actual epidemic, so I really wish all women asked their doctors to be tested.

Now, before you go to to your doctor to find out what your actual blood level is, refer to the Vitamin D Council’s recommendation on deficiency.

Make sure your doctor orders a 25-hydroxyvitamin D, or 25(OH)D, test, because old-school doctors have been known to order a 1,25-dihydroxyvitamin D test and new findings show that this can’t actually detect a true deficiency.

When You Decide to Supplement

If you and your doctor feel that you need more vitamin D than your prenatal vitamins offer, she may think to prescribe a pharmaceutical grade supplement known as calcitriol, which is a synthetic version. Not only will it not really help, it also has icky side effects. Scientists now understand that the best way to supplement Vitamin D is in the form of the more natural Vitamin D3. (More info here.)


If all of this was confusing, let me summarize: 

  • If you are pregnant, vitamin D dramatically influences you and your child.
  • Chances are really really good you are deficient.
  • Your vitamin D level should exceed 30 ng/mL.
  • You can find out for sure what your level is by asking your doctor to order a test called a 25(OH)D test.
  • When you supplement, use only Vitamin D3.
  • If you aren’t sure how much to take, refer to the Vitamin D Council’s information.

Click here to read more posts from Everything Birth about the importance of Vitamin D.



  1. Abbie

    Living in Alaska I have to be particularly aware of Vitamin D. Just had mine checked this week and I was at 51.2. I was pleased with this result but in order to be there I take 6,000 IU’s 4-5 times a week. That’s three of the 2,000 IU pills. The “safe” range is all the way up to 88. So I if I was really consistent with 6,000 IU’s I’d still be a-okay. If I happen to miss a couple days in a row I can always tell, my mood goes south, I’m tired and the insomnia gets really bad.

  2. Lilah

    I really appreciate your research on this because I was recently tested with vitamin D deficiency. So although I am not pregnant, it’s one of those supplements you don’t really think about but is just as important. So it’s interesting to know that it is also important during pregnancy.

  3. leanne

    We can all participate in a HUGE 5 year study on D3 levels which will tell us our initial blood level, then tell us and INDIVIDUALIZED amount we need to take daily to raise our levels to above 40ng which is the amount shown to have statistically significant reductions on ALL the disease / illness associated with VitD3 levels to date via research… and then monitor our blood status every 6 months thereafter for the next 5 years, each time adjusting the recommendation to an individual amount we should be taking daily to maintain optimal ( >40 ) levels. There is a low cost ($65 each test) which is involved in the voluntary participation, but this is not a lot more than you’d pay for the bloodwork out of pocket AND you are contributing to the scientific findings about the importance of VitD3 (they also ask a questionnaire about your health status over the 5 years as related to your blood levels of D3) to specific illness/disease. See here:

  4. leanne

    (1) Nearly every baby born to a mother getting only the recommended daily dose of vitamin D (400 IU/day) is born deficient

    (2) More than 80% of pregnant women are deficient in vitamin D, and these women are five times more likely to give birth to a deficient baby than mothers with adequate levels

    • Dawn

      Wow. Given a newborn would be deficient at this RDA, it certainly seems like we could improve infant mortality by merely up-ing a mothers vitamin D during pregnancy. Knowing what we know about the importance in vitamin D in nearly every known disease.

  5. Kim

    Thanks for the reminder that I need to replace my D3 supplement stash. As a nursing mama, I normally took 6,000 IU so that I wouldn’t need to supplement my babies. I’ll need to up it now that I’m pregnant again and nursing. I give my oldest (5) 2,000 IU daily. I have caramel-ish skin and my oldest is a beautiful chocolate color, so we definitely need the supplementation, since I know we’re not getting adequate amounts of sunlight.

  6. Pingback: The “Autism and Flu Correlation” study and its inevitable use in marketing the flu shot. — Everything Birth's Blog on Midwifery, Attachment Parenting, Cloth Diapers and More

  7. Pingback: Why a blood test to check your Vitamin D levels during pregnancy might be a good idea. — Everything Birth's Blog on Midwifery, Attachment Parenting, Cloth Diapers and More

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