Seven out of every 10 U. S. women who are pregnant may need to get more vitamin D, researchers have concluded.

Researchers at the University of Colorado School of Medicine in Denver, Massachusetts General Hospital and Children's Hospital Boston looked at the Centers for Disease Control and Prevention national sample data on 928 pregnant and 5,173 non-pregnant women of childbearing age.

Published in the American Journal of Obstetrics and Gynecology, the study suggested prenatal vitamins may raise vitamin D levels during pregnancy, but many women may need higher doses.

Lead author Dr. Adit Ginde of Denver says in a statement, "We already know vitamin D is important for bone health of the mother and infant, but we are just starting to scratch the surface about the many potential health benefits of vitamin D during pregnancy."

Vitamin D levels generally seem to be below what's considered healthy. However study co-author Dr. Carlos Camargo of Massachusetts General cautions there could be risks from excessive vitamin D intake, Ginde and colleagues have said.

Camargo further says, "We need more data from clinical trials of vitamin D supplementation in pregnant women. If the ongoing trials continue to show benefit, the best strategy will likely be measuring Vitamin D levels through a simple blood test and choosing supplementation doses according to those levels."

Ginde also adds, "This tailored approach is common in preventive care for people with high cholesterol, and safer and more effective than a one-size-fits-all solution." (With Inputs from Agencies)