In a bold move, MUSC Health has become the first health care provider in the nation to recommend that pregnant patients who are considered vitamin D–deficient take 4,000 international units, or IU, of vitamin D every day.

Neonatologist Carol Wagner called it a quantum leap in clinical practice. "It's already translated into benefits for our pregnant moms," she said.

Longtime Medical University of South Carolina vitamin D researcher Bruce Hollis agreed. "After many years of studying vitamin D in relation to improving birth outcomes, MUSC is the first academic institution to provide pregnant women with 4,000 IU of vitamin D daily, which is almost 10 times higher than the amount currently recommended by the government. We hope this will improve pregnancy outcomes, which the state of South Carolina chronically struggles with."

They point to research suggesting that getting enough vitamin D during pregnancy may help in several key areas, including:

• Preventing gestational diabetes
• Lowering the risk of preeclampsia
• Reducing the risk of asthma

And it may do much more than that, Wagner said. She's currently studying how vitamin D delivered to babies through breast milk affects their immune systems. She also wants to know just how much vitamin D the mother needs to take to benefit the baby. "We're comparing women who are on 400 international units versus 6,400 international units," Wagner said. "We're looking at differences in their immune system's signature that's given through their milk to see if there really is a difference."

Four hundred international units of vitamin D is the amount most prenatal vitamins contain. Wagner said that's probably not enough – in fact, not even close. Her position is based on previous research at MUSC and elsewhere, including a study of about 350 women conducted by Hollis, Wagner and colleagues. It found 4,000 IU per day for pregnant women was safe and didn't cause any harmful effects.

Meanwhile, MUSC Health obstetrician Roger Newman is looking at vitamin D's possible role in another area that can have a dramatic impact on babies: preterm birth, which can cause lifelong problems. He and his co–workers recently finished part of a field trial testing whether raising pregnant women's vitamin D levels to between 40 and 60 nanograms per milliliter of blood serum would lower the risk of giving birth prematurely.

"The preliminary results are very encouraging," Newman said. "There was a 65 percent lower risk of preterm birth for whites and 68 percent for non–whites."

Non–whites, who were mainly African–Americans in Newman's study, tend to absorb less vitamin D from the sun because their skin has more melanin. Melanin is a natural sunscreen.

Across the country, the babies of African–American women are 50 percent more likely to be born prematurely than the babies of white mothers. Newman said his research is not trying to suggest that vitamin D deficiency is the only potential cause – genetics and the environment almost certainly play important roles in causing premature births. But the obstetrician said vitamin D deficiency is well worth looking at, and it's a relatively simple problem to address.