Researchers have identified yet another reason to take that multi during pregnancy: It could reduce your child's risk of asthma. According to findings presented in March at the American Academy of Allergy, Asthma, and Immunology meeting in Miami, higher maternal vitamin D intake levels decreased a child's risk for developing asthma. Researchers from Harvard Medical School in Boston followed 1,194 mother-child pairs for more than three years and found that for every 100 IU/day increase in the mother's vitamin D intake during pregnancy, her child's risk of developing asthma decreased by as much as 20 percent.

Current vitamin D recommendations by the National Institutes of Health are 200 IU/day for pregnant women. But women in the study who lowered their child's risk for asthma most took more than twice that: 724 IU/day. "Current recommendations are too low," says Carlos Camargo, MD, DrPH, lead study author and professor of medicine and epidemiology at Harvard Medical School. Camargo recommends pregnant women "aim for 800 IU/day of vitamin D, through foods and/or supplements." (Good nonsupplement sources include sunlight, fortified milk, and fish such as salmon.) David Rosenstreich, MD, the director of the Division of Allergy and Immunology for Montefiore Medical Center in the Bronx, New York, agrees. "Getting a little extra vitamin D is probably a good idea, especially if your family has any kind of tendency toward an allergic disease or asthma."