Though the use of vitamin D supplements during pregnancy has been a matter of concern for mothers-to-be, new research indicates that even a high dosage of vitamin D is safe and effective for the pregnant women who need it. Even the highest amounts of vitamin D intake were not associated with any adverse effects in mothers or their newborns.

Previously, it was thought that vitamin D supplements could cause harm to the fetus. University of South Carolina researchers monitored the pregnancies of 350 women and assigned them to one of three groups.  One group received 400 IU of vitamin D per day, the second group received 2,000 IU per day and the third received 4,000 IU daily. The researchers found that women who received the highest dose of vitamin D (4,000 IU per day) were more likely to achieve and sustain the desired level of circulating levels of vitamin D throughout their pregnancy.

The two other groups did not achieve desired levels. “In our study subjects, a daily dosage of up to 4,000 IU of vitamin D was required to sustain normal metabolism in pregnant women,” said lead researcher Dr. Bruce Hollis from the Medical University of South Carolina in Charleston. Vitamin D has also been linked to a number of other health benefits, including strong bones, low blood pressure and protection from autoimmune diseases. A study conducted by Stanford researchers, unrelated to this one, has even found evidence that vitamin D may protect against skin cancer. Besides supplements, the largest source of vitamin D is actually sun exposure.

Vitamin D can also be found in eggs, fortified milk and fatty fish, such as salmon. The study was published in the Journal of Bone and Mineral Research.