New York — NEW YORK — HIV-infected women who breastfed without supplementing their infants' diets with other fluids or foods for the first six months of life had lower levels of the AIDS virus in their milk, a study in Zambia showed.
The findings, published Wednesday in Science Translational Medicine, are the first to show how variations in breast-feeding practices affect HIV levels in an infected mother's milk. Women who stopped breast feeding had "dramatically higher" levels of the virus, said Louise Kuhn, lead author of the study.
Early weaning hasn't been successful in preventing HIV transmission from mother to baby, and the study may help explain why, said Kuhn, an associate professor of epidemiology at Columbia University's Mailman School of Public Health in New York. While it's unknown why breastfeeding lowers HIV levels, researchers hypothesize the "hormonally regulated, demand- supply" cycle of frequent breastfeeding may influence HIV dynamics in breast milk.
"Weaning should be a slow and gradual process," Kuhn said in an email.
HIV-positive women who choose to breastfeed should adhere to their antiretroviral drug regimens and exclusively breastfeed through the first six months before gradually introducing complementary foods and continuing to breastfeed until they and their infants are ready to wean, Kuhn said.
Researchers looked at the breast milk of 958 HIV-infected women and their infants and followed them for two years. They were trying to determine whether shortening the duration of breastfeeding would reduce the risk of HIV transmission.
All the women were to breastfeed their babies for at least four months, then half the women were recommended to stop while the other half was encouraged to continue. The women had their breast milk collected at four and a half months, and the babies in the study were routinely tested for HIV transmission.
Findings showed that 77 percent of the women who had stopped breastfeeding at four months had detectable levels of HIV in their breast milk compared with 40 percent of those who were still exclusively breastfeeding at 4 1/2 months. Women who supplemented their breastfeeding after four months with other fluids and foods had higher HIV concentrations in their breast milk than those who were exclusively breastfeeding, though the level was lower than those who had weaned, the study found.
At the time of the study, antiretroviral drugs weren't available for the treatment of advanced HIV in sub-Saharan Africa, she said. When they were available, they were only used around the time of delivery and not recommended for use during breastfeeding. Women could choose to breastfeed and risk passing along the virus to their child or they could not breastfeed, which would leave their baby at a higher risk of infectious diseases like pneumonia and diarrhea.
"Fortunately since such time as we conducted the research, antiretroviral drug regimens have now been shown to be highly effective to prevent transmission through breastfeeding," she said. "Governments should support the roll-out of programs to make antiretroviral drugs available for HIV-positive women who are pregnant and who are breastfeeding."
Antiretroviral treatments include Johnson & Johnson's Prezista, Gilead Sciences Inc.'s Truvada, Bristol-Myers Squibb Co.'s Sustiva, GlaxoSmithKline Plc's Ziagen and Abbott Laboratories's Kaletra.
In 2010, the World Health Organization updated its breast- feeding guidelines for HIV-positive women to recommend that each country decide which infant feeding practice they want to promote, including whether antiretroviral drugs be used to reduce the transmission of the virus during breastfeeding or breastfeeding be avoided.
The WHO guidelines suggest that where HIV treatments are used, mothers should breastfeed their infants to at least 12 months. And if antiretroviral drugs are unavailable, women can still breastfeed for at least the first six months.
The U.S. Centers for Disease Control and Prevention advises HIV-positive women not to breastfeed their infants even if they are taking antiretroviral drugs.