The Most Important Thing to Know About Vitamin D and Pregnancy

Pregnant Woman

What is the most important thing to remember about vitamin D and pregnancy? Most pregnant women need to take more vitamin D, a lot more.

Vitamin D and Pregnancy Complications

A research team at the Medical University of South Carolina recruited 500 women to participate in a study of the effects of taking vitamin D after the first trimester. Since overdoses of other fat-soluble vitamins have been associated with birth defects in the first trimester, they did not include women who had been pregnant for three months or less.

Women were asked to take 400 IU, 2,000 IU, or 4,000 IU of vitamin D each day. Then at the end of their pregnancies, the research doctors considered whether or not they had experienced any complications. The University of South Carolina research team found that women who had taken 4,000 IU of vitamin D every day:

Vitamin D Makes a Potentially Life-Saving Difference

The research team did not find a single report of any adverse effect of vitamin D in any of the women who took it. Dr. Bruce Hollis, director of pediatric nutritional science at the medical school, said, "Pregnant women need to take 4,000 IU of vitamin D a day. We didn't see a single adverse effect. It was absolutely safe, and we saw a lot of improved outcomes. The risk of preterm labor was vastly decreased and so was the risk of other complications of pregnancy."

Notably absent in the mothers who took 4,000 IU of vitamin D a day was a condition called preeclampsia. In this condition, low levels of calcium and magnesium lead to extremely high blood pressure that can be dangerous to both mother and unborn child. Preeclampsia is the leading cause of death of women during pregnancy, and a leading reason for miscarriage. Vitamin D helps tissues receive the calcium they need, not just to build healthy bones, but also to manage heartbeat and the flexibility of blood vessels.

Vitamin D May Prevent Autism

Scientists have known for a long time that children who were born in the spring and early summer are especially likely to suffer autism. Scientists have also observed that mothers who have more upper respiratory infections during pregnancy are more likely to give birth to autistic offspring.

And the reason some pregnant women get more colds and flu than others may be vitamin D deficiency. Having adequate amounts of vitamin D in circulation stops the inflammation that goes along with these infections. Stopping the inflammation caused by the infection may protect the unborn child's brain from inflammation, and lower the likelihood of being born with autism.

Vitamin D supplementation is most likely to be needed by women who live north or south of 35 degrees of latitude during the winter (north of Los Angeles, Atlanta, southern Spain, southern Turkey, New Delhi, or Shanghai, or south of Sydney, Auckland, or Buenos Aires) and women who have dark skin. Women who cannot go out during summer heat, even in sunny climates, may also become vitamin D deficient. The city of Atlanta in the United States has an unusually large number of women with this kind of vitamin D deficiency. Taking vitamin D will correct deficiency.

How Much Vitamin D Should Pregnant Women Take?

To get the recommended 4,000 IU of vitamin D a day, pregnant women need to consume, daily:

For getting your vitamin D from completely natural sources, cod liver oil is the only practical option. However, four tablets of any 1,000 IU vitamin D supplement, probably costing less than US $0.10, provides all the D any expectant mother needs for a healthy delivery. Start taking vitamin D only after the first trimester.

Selected Reference:

Hamilton SA, McNeil R, Hollis BW, Davis DJ, Winkler J, Cook C, Warner G, Bivens B, McShane P, Wagner CL. Profound Vitamin D Deficiency in a Diverse Group of Women during Pregnancy Living in a Sun-Rich Environment at Latitude 32°N. Int J Endocrinol. 2010;2010:917428. Epub 2010 Dec 9.