Harvard researchers discovered that HIV-positive women taking vitamin A are almost a third more likely to transmit the virus to their infants than mothers who do not take the vitamin.

The study, which will be published Sept. 27 in the journal AIDS, raises concerns about current AIDS prevention strategies in the developing world, where multivitamins—including vitamin A—are used in areas where anti-retroviral treatments and other drugs that prevent mother-to-child transmission are prohibitively expensive.

“Our findings give little encouragement for the use of vitamin A supplements in HIV-positive pregnant women,” said Wafaie Fawzi, lead author of the study and associate professor of nutrition and epidemiology at the Harvard School of Public Health (HSPH).

HSPH researchers cooperated with Muhimbili University College of Health Services in Dar es Salaam, Tanzania to randomly assign 1,000 HIV-infected pregnant women in Tanzania to groups taking either vitamin A, multivitamins excluding A and including B, C, and E, multivitamins including A, or a placebo.

Women in the study received the supplements from the twentieth week of pregnancy through lactation.

After making monthly clinic visits to examine the supplement’s effects on HIV transmission and on childhood mortality in the first two years of life, the researchers found that the mothers who had received vitamin A supplements during their pregnancies had a 42.4 percent transmission rate, while those who did not had a 33.8 percent transmission rate.

Researchers also learned that, for women with poor nutrition and weak immune systems, multivitamins excluding vitamin A reduce rates of early child mortality and of HIV transmission via breast milk, defined as infection after six weeks of age among those who were not known to be infected previously.

In the past, mother-to-child transmission of HIV has been attributed in part to poor maternal nutrition.

In many regions of Africa, between 15 and 30 percent of women attending prenatal care clinics are HIV positive.

Twenty to 45 percent of children born to HIV-positive mothers become infected through breastfeeding or during pregnancy, labor or delivery, according to the study.

Fawzi stressed, though, that his findings should not raise concerns about ongoing child programs that provide vitamin A supplements starting as six months of age.

—Staff writer Maria S. Pedroza can be reached at mpedroza@fas.harvard.edu.