Vitamin D's surprising impact on pregnancy

Vitamin D's surprising impact on pregnancy

At the birth center where I work in Concord, we perform all the labs that someone would receive from any conventional obstetric provider, so I spend quite a bit of time reviewing things like iron, blood-born pathogens, and so on. But, there's one test that we routinely offer that my doula clients birthing in hospitals almost never have performed: Vitamin D.

Here in New England, almost all of the clients that I've seen are low on Vitamin D, and sometimes critically deficient (guess what...I was!). The normal range is between 30-70, and I've come to expect clients to fall somewhere between 15-25. Why is this a big deal?

Because studies suggest that low Vitamin D is associated with...

Vitamin D is produced when the UV light of the sun hits our skin. When we synthesize Vitamin D, it's used in a wide variety of processes--impacting everything from our immunity, mood, metabolism, how our hormones work, and bone growth to our baby's brain development and our children's long-term health--or stored in the liver. In particular, it helps our bodies absorb calcium, which is why low D can cause so many problems in pregnancy.

It didn't surprise me that so many people I see have low Vitamin D--after all, we have such long winters here--but I was surprised to recently learn that no one in the northern hemisphere can make vitamin D between the months of November and February, because it has to do with the angle of the sun's rays on the earth and not the amount of sun (of course, you might be more tempted to be outside if you lived in Florida and could go swimming in March. Can't do that in New Hampshire. It's too cold for me to swim even in July). 

Plus, our deficiencies are more about lifestyle than anything else. We need time outside, with our arms and legs exposed, for at least 15 minutes (for lighter skinned people) to up to 2 hours (for darker skinned people). And because it's formed on our skin, if we shower after we come inside, we don't actually absorb as much Vitamin D as we produce. Some things that can make it harder to absorb D include: long days at work, air pollution, keeping your skin covered for religious or other reasons, sunscreen, and so on (Cairo friends--I'm looking at you!).

 "Lenora," Zdenek Milker (1957)

"Lenora," Zdenek Milker (1957)

Well, what about vitamin D in foods, as in milk with Vitamin D added? There are two forms of Vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). D2 is added to milk and orange juice, and D3 is naturally present in cold-water fish, egg yolks, and butter. Yet, D3 is actually easier for the body to assimilate, and is more likely to bring up levels of Vitamin D, so consuming fortified products might not really be all that helpful when we're very deficient.

One last thing to consider is the way that Vitamin D acts alongside other nutrients such as calcium, magnesium, vitamin A, and Vitamin K. In particular, Vitamin K2 (found in abundance in liver, pastured egg yolks, pastured dairy, and natto), works with Vitamin D to put calcium where it belongs (instead of getting gunked up as plaque on teeth, in blood vessels, or on our placentas). So, it's a good idea to take a Vitamin D supplement that contains both D3 and K2--I particularly like this one from Thorne.

The takeaway:

  • Have your Vitamin D levels checked when your prenatal labs are performed, or at any point in your pregnancy.
  • If you're deficient in Vitamin D, find a D3 supplement. It's safe to take up to 5,000 IUs in pregnancy. 
  • After 8 weeks of daily supplementation, have your Vitamin D levels checked again to see whether they're improving.
  • If your levels are normal, supplement with 1,000-2,000 daily in the winter as a maintenance dose.
  • During the spring through fall, hang out in the sun. Determine how much time you need based on how dark or light your skin is.
  • If you cover your arms and legs outside and rarely expose them, supplement with Vitamin D year-round.
  • It's recommended that infants and children received 400 IUs of Vitamin D daily. If you're breastfeeding and you supplement with 6,000 IUs, then your baby will get all the Vitamin D needed from your milk.
  • Cod liver oil is an excellent source of Vitamin D, as well as other fat soluble vitamins and omega-3 fatty acids and is an excellent supplement to take throughout your life (yes--including in pregnancy, if you're concerned about Vitamin A then read this about the difference between natural, animal-derived Vitamin A and synthetic Vitamin A). My grandmother was so right! Thankfully, it tastes way better now than when I was five. Read more on the benefits of CLO here, and check out other food sources of Vitamin D here.

Further reading:

  • The Dental Diet  - This is a great book on dental care and nutrition (and since dental health is a reflection of overall health and nutrition, then this book is for your whole body). I love Steven Lim's clear explanations of how the fat-soluble vitamins A, D, and K2 work together. Here's a blog post he wrote on Vitamin D and dental health.
  • Real Food for Mother and Baby - This book by Nina Planck explores the role that quality animal proteins and fats play in our fertility, pregnancy, and early growth. For a more specific text on babies and children, check out the Nourishing Traditions Book of Baby & Child Care.
  • More on Cod Liver Oil from the Weston Price Foundation archives
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