Routine vitamin D screening in pregnancy not ACOG-endorsed

Available evidence doesn’t support screening all pregnant women for vitamin D deficiency, the Committee on Obstetric Practice of the American College of Obstetricians and Gynecologists concludes in an opinion published in Obstetrics and Gynecology (2011;118[1]:197-198).

The committee recommends considering maternal serum
25-hydroxyvitamin D (25-OH-D) levels in pregnant women suspected to be at increased risk for vitamin D deficiency (ie, vegetarians, women with limited sun exposure, and ethnic minorities, especially those with darker skin) and interpreting the levels in the context of each woman’s clinical situation.

“When vitamin D deficiency is identified during pregnancy, most experts agree that 1,000-2,000 international units (IUs) per day of vitamin D is safe,” the committee writes. “Higher dose regimens used for the treatment of vitamin D deficiency have not been studied during pregnancy,” although most experts concur that as much as 4,000 IU of vitamin D supplementation daily is safe for pregnant and lactating women.

The committee adds that “recommendations concerning routine vitamin D supplementation during pregnancy beyond that contained in a prenatal vitamin should await the completion of ongoing randomized clinical trials.” They also note that insufficient evidence exists to recommend vitamin D supplementation to prevent preterm birth or preeclampsia.

The optimal serum level of 25-OH-D in pregnant women hasn’t been established. A serum level of at least 20 ng/mL (50 nmol/L) is generally considered necessary to prevent bone problems. Some experts have suggested defining vitamin D deficiency as circulating 25-OH-D levels less than 32 ng/mL (80 nmol/L), based on biomarkers of vitamin D activity such as parathyroid hormone, calcium absorption, and bone mineral density.