How much Vitamin D does a pregnant woman need? According to a new study high doses of Vitamin D– 4,000 international units (IU) per day– are best. Research shows that it may reduce the risks of preterm labor, gestational diabetes, pregnancy-related high blood pressure, preeclampsia, and infection.

The more the better?

Although this is at least 10 times the amount recommended by various health groups, women in the study showed no evidence of harm. On the contrary, they had half the rate of pregnancy-related complications as women who took only 400 IU  every day. (For reference, most prenatal vitamins contain 400 IU of vitamin D.)

Controversial findings

Why are these findings so controversial?  Until now, very high doses of vitamin D have long been believed to cause birth defects. But neonatologist and study co-researcher Carol L. Wagner, MD, says that there is no evidence that vitamin D supplementation is toxic, even at levels above 10,000 IU.

Wagner says it took months to get permission to do this study, in which pregnant women were given such high doses of the vitamin.  About 500 women in Charleston, S.C.,  in their third or fourth months of pregnancy, took 400 IU, 2,000 IU, or 4,000 IU of vitamin D daily until they delivered.  The women who took the highest doses had the lowest rate of pregnancy-related complications.

Vitamin D Sources

You can get vitamin D from some foods, like fortified milk and fatty fish,  but few people get the vitamin D they need through food.  The body makes vitamin D from sunlight, but even in sunny climates like Charleston, few people are getting adequate levels of sun exposure.

Babies need vitamin D, too

Breastfed babies whose mothers have low vitamin D levels and who don’t take vitamin supplements are likely to be deficient, too. Vitamin D drops are likely to be prescribed. But not surprisingly, pregnant women who take high doses of vitamin D give birth to babies who are less likely to be vitamin D deficient.

Read more at WebMD: High Doses of Vitamin D May Cut Pregnancy Risks

Feature image from Kristi Cares: The Kristina A. Stockley Melanoma Foundation