Even among those taking prenatal multivitamin supplements, vitamin D was found to be deficient in pregnant women, particularly in African-American women and women living in northern regions. Researchers at University of Pittsburgh, PA, took blood samples from 400 pregnant women—200 black women and 200 white women—before 22 weeks gestation and again after delivery.
"In our study, more than 80% of African American women and nearly half of white women tested at delivery had levels of vitamin D that were too low, even though more than 90% of them used prenatal vitamins during pregnancy," says lead author Lisa Bodnar, Ph.D., M.P.H., R.D., assistant professor of epidemiology, University of Pittsburgh Graduate School of Public Health.
Further, umbilical cord blood from newborns showed 92.4% of African American babies and 66.1% of white infants had insufficient vitamin D levels at birth, leaving them at risk for rickets and other health problems. "A newborn's vitamin D stores are completely reliant on vitamin D from the mother," observes Bodnar.
Vitamin D deficiency early in life is associated with rickets, a disorder characterized by soft bones.
Finding such a proliferation of vitamin D insufficiency in spite of prenatal multivitamin use is troubling, Bodnar notes, suggesting that higher dosages, different vitamin formulations or a moderate increase in sunlight exposure might be necessary to boost vitamin D stores to healthier levels.
Primary dietary sources of vitamin D include fatty fish, fortified foods such as milk, some ready-to-eat cereals and vitamin supplements. Sun exposure for skin synthesis of vitamin D remains critical.
The study was published in the Feb. issue of The Journal of Nutrition (2007; 137:447-452) and is available online at http://jn.nutrition.org/cgi/content/abstract/137/2/447.