Why you need vitamin D during pregnancy
Your body needs vitamin D to maintain proper levels of calcium and phosphorus, which help build your baby's bones and teeth.
What happens if you don't get enough vitamin D
Vitamin D deficiency is common during pregnancy. Inadequate vitamin D can lead to abnormal bone growth, fractures, or rickets in newborns.
Some studies link vitamin D deficiency to a higher risk of pregnancy complications such as gestational diabetes, preeclampsia, preterm birth, and low birth weight, but more research is needed to confirm these links.
The symptoms of a vitamin D deficiency can be subtle. They may include achy muscles, weakness, bone pain, and softened bones, which may lead to fractures.
You can also have a vitamin D deficiency without any symptoms. And if that happens while you're pregnant, your baby can suffer a deficiency, too.
How much vitamin D you need
Vitamin D dosage is a topic of debate. The Institute of Medicine currently recommends that all women – whether or not they're pregnant or breastfeeding – get 600 international units (IU) of vitamin D or 15 micrograms (mcg) each day.
But many experts believe that 600 IU isn't nearly enough. The Linus Pauling Institute, for example, recommends all adults take 2,000 IU of supplemental vitamin D each day. The Endocrine Society says 600 IU may be enough, but some people – including pregnant and breastfeeding women – may need 1,500 to 2,000 IU of vitamin D.
In 2015, the American College of Obstetricians and Gynecologists stated that more safety research is needed before the organization would recommend more vitamin D than what's in a standard prenatal vitamin. Ask your healthcare provider for advice about how much vitamin D you need during pregnancy.
Food sources of vitamin D
Fish liver oil, fatty fish, and eggs all contain vitamin D. But not many other foods contain vitamin D naturally, so a lot are fortified with this important vitamin. Be sure to check labels: Some cheeses, yogurts, and cereals are fortified while others aren't. (All milk is vitamin D fortified.)
Here are some of the best food sources of vitamin D:
- 3 ounces canned pink salmon: 465 IU (11.6 mcg)
- 3 ounces canned mackerel: 211 IU (5.3 mcg)
- 3 ounces canned sardines: 164 IU (4.1 mcg)
- 8 ounces orange juice, fortified with vitamin D: 100 IU (2.5 mcg)
- 8 ounces low-fat milk, fortified with vitamin D: 98 IU (2.5 mcg)
- 1 cup cereal, fortified with vitamin D: 40 to 50 IU (1.0 to 1.3 mcg)
- one large egg yolk: 37 IU (0.9 mcg)
Should you take a vitamin D supplement?
Maybe. Most prenatal vitamins only contain 400 IU (10 mcg) of vitamin D, and it's difficult to get sufficient vitamin D from foods alone, even when you choose fortified foods.
Since the skin uses the sun's rays to produce vitamin D, some experts recommend limited sun exposure, while others caution against it without the protection of sunblock and clothing. Exposure to the sun's ultraviolet [UV] rays intensifies the pigment changes that cause irregular skin darkening in pregnant women, so most doctors recommend that pregnant women protect themselves from the sun and get their vitamin D from food or supplements.
Factors that might put you at risk for a vitamin D deficiency include:
- Obesity. Because body fat stores much of the vitamin D made in the skin, it's less available to the body. (Vitamin D that you get from food and supplements appears to be more available to the body, so those are more reliable sources.)
- Darker skin. People with darker skin have a lot of melanin, which acts as a natural sunscreen and reduces production of vitamin D in the skin.
- Certain medications. Medications such as steroids, antiseizure medications, cholesterol-lowering drugs, and some diuretics reduce absorption of vitamin D from the intestines.
- Fat malabsorption conditions. Disorders such as celiac disease and Crohn's disease involve a reduced ability to absorb dietary fat, and that leads to less absorption of vitamin D.
If you're worried about not getting enough vitamin D, ask your healthcare provider if you should be tested for a deficiency or if you need to take a vitamin D supplement. When choosing a supplement, look for the kind labeled vitamin D3, or cholecalciferol, which is the most effective form. (Vitamin D2, or ergocalciferol, is about 25 percent less potent.)