High Doses of Vitamin D May Cut Pregnancy Risks
Study Shows 4,000 IU a Day of Vitamin D May Reduce Preterm Birth and Other Risks
WebMD News Archive
May 4, 2010 -- Women who take high doses of vitamin D during pregnancy have
a greatly reduced risk of complications, including gestational diabetes,
preterm birth, and infection, new research suggests.
Based on the findings, study researchers are recommending that pregnant
women take 4,000 international units (IU) of vitamin D every day -- at least 10
times the amount recommended by various health groups.
Women in the study who took 4,000 IU of the vitamin daily in their second
and third trimesters showed no evidence of harm, but they had half the rate of
pregnancy-related complications as women who took 400 IU of vitamin D every
day, says neonatologist and study co-researcher Carol L. Wagner, MD, of the
Medical University of South Carolina.
Wagner acknowledges the recommendation may be controversial because very
high doses of vitamin D have long been believed to cause birth defects.
"Any doctor who hasn't followed the literature may be wary of telling their
patients to take 4,000 IU of vitamin D," she says. "But there is no evidence
that vitamin D supplementation is toxic, even at levels above 10,000 IU."
Fewer Complications With High Vitamin D Doses
Most prenatal vitamins have around 400 IU of vitamin D, and most health
groups recommend taking no more than 2,000 IU of the vitamin in supplement form
daily. Wagner says it took months to get permission to do a study in which
pregnant women were given doses of the vitamin that were twice as high as
The study included about 500 women in Charleston, S.C., who were in their
third or fourth months of pregnancy. The women took 400 IU, 2,000 IU, or 4,000
IU of vitamin D daily until they delivered.
Not surprisingly, women who took the highest doses of vitamin D were the
least likely to have deficient or insufficient blood levels of the vitamin, as
were their babies.
These women also had the lowest rate of pregnancy-related complications.
Compared to women who took 400 IU of vitamin D daily, those who took 4,000
IU were half as likely to develop gestational diabetes, pregnancy-related high
blood pressure, or preeclampsia, Wagner says. They were also less likely to
give birth prematurely.