When Breastfeeding with HIV, Timing is Everything

For much of the past decade, Jean Humphrey's work in Zimbabwe with pregnant women and new mothers has been guided by a tragic statistic: 40 percent of mother-to-child HIV infections are caused by breastfeeding. Yet breastfeeding also protects against life-threatening infections, and directly prevents at least 1.3 million infant deaths worldwide each year.

International health guidelines advise HIV-positive mothers to avoid breastfeeding when an alternative source of nourishment is "acceptable, feasible, affordable, sustainable and safe." But in Zimbabwe, where 21 percent of pregnant women are HIV positive, meeting those conditions is virtually impossible because of economic and cultural factors. Most poor women in rural, isolated areas cannot afford infant formula and do not have access to potable water. 

"Breastfeeding is really the only nutritionally adequate, safe food for infants in rural Africa, and to remove that is really hoisting an enormous burden onto families that are already really struggling," says Humphrey, ScD '92. An associate professor of International Health at the Bloomberg School, Humphrey has made it her goal to help identify the least risky ways for HIV-positive mothers to feed their babies. 

Her research, and that of scientists in other African nations, indicates that exclusive breastfeeding in a baby's early months may substantially reduce mother-to-infant HIV transmission. These early months are also when the risk of infant death due to not breastfeeding is particularly high. As babies grow older, the risk declines, but the risk of HIV transmission remains relatively constant. 

"At some point these lines will cross, and it may become more risky to breastfeed than not," Humphrey says.

To help HIV-positive mothers stop breastfeeding at about six months, Humphrey launched a pilot study earlier this year to identify alternative infant feeding options. The goal is to be able to tell mothers "with some confidence that another diet would support the health of the baby," she says.

Humphrey's work takes place within the context of the ZVITAMBO project, initiated by the School in 1997 as a randomized clinical trial to test the effects of post-partum vitamin A supplementation on maternal and infant health. Most of ZVITAMBO's funding comes from the Canadian International Development Agency, the U.S. Agency for International Development and the Bill and Melinda Gates Foundation. As researchers learned more about breastfeeding-associated HIV infection, Humphrey and other ZVITAMBO scientists developed education and counseling interventions—including classes on safer breastfeeding practices and educating women about the importance of knowing their HIV status—to inform mothers about the risks and benefits of different feeding choices. 

In the pilot study that is under way, Humphrey's team did in-depth interviews with mothers to gather information on infant diets, the availability of local foods and cultural attitudes related to early cessation of breastfeeding. 

She hopes the study will lead to a randomized trial to compare different diets for babies between six and 12 months born to HIV-positive mothers. The use of safe feeding alternatives could potentially avert 25 percent of breastfeeding-associated HIV infections, Humphrey says. Possible breast milk replacements include a corn and soy mixture and a peanut butter-based micronutrient blend. "We're hoping that more of them [HIV-positive mothers] might be able to stop [breastfeeding] at 6 months," she says.

During her time in Zimbabwe, Humphrey has become accustomed to the challenges of doing research in a poor and economically unstable country. Regular power outages occur three or four times a week, threatening the quality of thousands of blood specimens in ZVITAMBO's lab freezers. And skyrocketing inflation rates in the past six years have created shortages of foreign currency, fuel and food. 

Despite such challenges, Humphrey has no plans to leave. "I have generally said that I'll stay as long as I'm welcome and can be doing something productive."