Exclusive breastfeeding lowers mother-to-child HIV risk

HIV-infected women who fed their babies exclusively with breast milk for more than the first four months of life had the lowest risk of transmitting the virus to their babies through breast milk, according to a new study published online in the journal Science Translational Medicine on Wednesday. HIV-infected women typically have a 10 percent to 15 percent chance of transmitting the virus to their babies through breast milk. However, breast milk contains many important components that help developing immune systems fend off infectious diseases and health experts believe that in sub-Saharan Africa where infectious diseases are rampant and often life-threatening, breastfeeding is essential for keeping infants healthy. To test whether changes in breastfeeding routines affect levels of HIV in breast milk, researchers at the Columbia University's Mailman School of Public Health followed over 900 HIV-infected women and their babies in Zambia for two years. All of the women were counseled to breastfeed at birth for at least four months. At four months, half of the women were encouraged to stop breastfeeding, while the other half were encouraged to continue. Breast milk was collected from all women at four and a half months. Throughout the study, infants were tested regularly for possible HIV transmission. The researchers found the highest concentrations of HIV in the breast milk of women who stopped breastfeeding at four months. More than 77 percent of the women who had stopped breast feeding had detectable concentrations of HIV in their breast milk compared to 39.5 percent of those exclusively breastfeeding at four and a half months. The two groups of women had showed no differences two weeks earlier at four months. Women who continued to breastfeed, but not exclusively, had higher breast milk HIV concentrations than those practicing exclusive breast feeding. The researchers said that the results offer evidence that even subtle changes in the frequency of breastfeeding during infancy can affect concentrations of HIV in breast milk. "Our results have profound implications for prevention of mother to-child HIV transmission programs in settings where breast-feeding is necessary to protect infant and maternal health," wrote Louise Kuhn, Mailman School professor of epidemiology. "Our data demonstrate that early and abrupt weaning carries significant risks for infants."