The Importance of Vitamin D During Pregnancy

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Vitamin D During PregnancyVitamin D deficiency is extremely common among pregnant women. How much Vitamin D should you take during pregnancy?

 What if I told you that taking Vitamin D may help reduce your risk for diabetes, heart disease, gut and immune problems, excess weight, weak bones, as well as prostate, breast, and colon cancer? (1).

What if I also told you that this same vitamin may reduce your risk for food allergies, infections, autoimmune disorders, and brain and nervous system disorders such as schizophrenia and multiple sclerosis?

Now, new research shows that Vitamin D may play critical roles in reducing additional health risks during pregnancy for both the mother and the child.

Questions to be Answered:

Part I:

  • Who's at risk for vitamin D deficiency?
  • How prevalent is vitamin D deficiency in pregnant women?
  • What are the risks to pregnant women due to vitamin D deficiency?
  • What are the long-term concerns of vitamin D deficiency to a developing baby?
  • How does vitamin D work beyond bone health?
  • & Lastly, how much vitamin D should I take if I'm pregnant or breastfeeding?

Who's at Risk for Vitamin D Deficiency?

Before we look closer to vitamin D deficiency in pregnancy, it's important to note that a variety of lifestyle factors have also been documented to play a role in Vitamin D deficiency such as:

  • darker skin color
  • clothing type (such as wearing a veil, or living in cold environments)
  • heavy use of sunscreen
  • living in northern latitudes (roughly estimated as everything north of Florida)
  • & living in areas with high urban pollution (smog)


Beyond lifestyle factors, the best ways to improve your Vitamin D intake is to expose your skin to the sun without developing sunburn, to take vitamin D supplements, and to increase your intake of dietary sources of vitamin D such as fortified milk & cereals, as well as fatty, oily fish like salmon, mackeral or sardines.

Some experts recommend that individuals preferentially seek vitamin D from exposure to sunlight or supplements because dietary sources of vitamin D are not likely to provide high enough levels to prevent health risks beyond rickets and weak bones (3).

In fact, a small study of 64 pregnant women showed that their total dietary intake of Vitamin D from dietary sources throughout their pregnancy was actually 80% below current recommendations (4)!

Prevalence of Vitamin D Deficiency in Pregnancy

Vitamin D deficiency is widespread and is increasingly recognized as a significant public health issue. Beyond the risk factors discussed above, deficiencies in pregnant mothers may be even be worse due to the increased demand for Vitamin D from the growing fetus (5).

As a result, infants who consume breastmilk from mothers deficient in vitamin D are also at high risk of vitamin D deficiency and related health problems.

It is estimated that vitamin D deficiency exists in 5-20% of light-skinned individuals & 30-70% of dark-skinned populations at or near the time of pregnancy (1).

A more recent August 2011 review similarly noted that 5-29% of pregnant women may be deficient in vitamin D, and also confirmed that African-American women were at even greater risk (6).

Lastly, many pregnancies go unplanned. Although it's seldom discussed, mothers do not always have the time (or the choice) to actively restore levels of nutrients such as vitamin D prior to becoming pregnant. For these reasons, screening for vitamin D deficiency is encouraged for women at risk of becoming pregnant, especially those at high risk of vitamin D deficiency (7).

What are the Risks to Pregnant Women Due to Vitamin D Deficiency?

Pregnant women with inadequate levels of vitamin D may have higher incidences of:

  • infertility such as failed implantation of embryo in uterine wall
  • preecclampsia (high blood pressure during pregnancy)
  • gestational diabetes
  • birth by cesarean section (up to 400% higher rate).
  • vaginal infections
  •  immune intolerance
  • multiple sclerosis

(891011; 12; 13; 14; 15).

To reduce these risks, research has shown that the actual dietary requirement during pregnancy and lactation may actually be as high as 6000 IU/day (16) - much higher than current recommendations of 600IU-800IU/day (which was only recently increased from 400IU/day).

Despite some concerns regarding high doses of Vitamin D, a June 2011 double-blind, randomized trial of 350 pregnant women showed that a dose of 4000IU/day of vitamin D was a safe and effective means of improving Vitamin D levels. In fact, not one adverse event was noted in the study.

The study also showed that current vitamin D recommendations were still inadequate at improving Vitamin D status, especially in African-American women. Those research subjects receiving the highest doses of vitamin D saw the greatest improvements in their vitamin D levels (17).

Stay tuned to read Part 2 for a continued discussion of vitamin D deficiency in infancy & the potential for long-term health risks. I will also briefly look at some thoughts as to how vitamin D actually works, and lastly, I'll offer some research suggestions for vitamin D intake during pregnancy and breastfeeding.

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Dr Alex Rinehart

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