The motherly advice of “a vitamin a day” got powerful new support from a clinical trial of 1,000 HIV positive pregnant women in Tanzania. Scientists from the Harvard School of Public Health report that among mothers-to-be taking a daily multivitamin tablet, rates of severely premature births and low birth-weight babies were dramatically lower than for those on placebos (none of the participants received antiretroviral drugs); women given the vitamins also had significantly higher CD4 cell counts. Giving a single nutrient (vitamin A) did not provide such benefits, the researchers noted.