African-American and Puerto Rican women who have low levels of vitamin D during pregnancy are more likely to go into labor early and give birth to preterm babies, research led by the University of Pittsburgh Graduate School of Public Health reveals. The study, funded by the National Institutes of Health, will be published in an upcoming issue of the American Journal of Epidemiology and is available online now. “Vitamin D is unique in that while we get it from our diets, our primary source is our body making it from sunlight,” said lead author Dr. Lisa Bodnar, associate professor in the department of epidemiology. “Previous studies using conservative definitions for vitamin D deficiency have found that nearly half of Black women and about five percent of White women in the United States have vitamin D concentrations that are too low.”