Does breast-feeding accelerate AIDS?

In developing countries, a child born to a mother infected with HIV–the AIDS virus–faces long odds against survival. Some babies are born already infected, and the others run the risk of acquiring the virus through breast milk. Feeding a child formula avoids that hazard, but it’s less healthy for the baby in other ways and more expensive for the family (see related story, http://www.sciencenews.org/20010602/note10.htm).

A study in Kenya now suggests that mothers with HIV who nurse infants are themselves more likely than formula users to die within 2 years of a child’s birth. This comes as chilling news because other research has shown that if a mother dies, her baby is up to four times as likely as others to die while still a child.

In 1992, a U.S.-Kenyan research team began designating groups of HIV-infected pregnant women to bottle- or breast-feed their infants. The women, who had all volunteered, were randomly assigned to a group. Of 200 women who fed their babies formula, 6 women died within 2 years. Of 197 who nursed their infants, 18 women died in that time, the team reports in the May 26 Lancet.

The researchers propose two scenarios to explain the correlation. When lactating, women produce the hormone prolactin, which stimulates breast-milk production. The hormone might suppress the immune system and somehow accelerate the course of AIDS, the researchers hypothesize.

On the other hand, women who breast-fed their babies lost more weight on average during the 9 months after giving birth than the mothers who bottle-fed their babies did. This suggests that breast-feeding steals nutrients from women and might make them more susceptible to AIDS, says study coauthor Joan K. Kreiss, an epidemiologist at the University of Washington in Seattle.

In a commentary accompanying the Lancet article, Marie-Louise Newell of the Institute of Child Health in London doubts the scenario theory because breast-feeding doesn’t seem to increase the death rate of women in famines.

While it’s tempting to discourage all breast-feeding among HIV-infected women in poor countries, the choice is not simple, says Robert J. Biggar, a pediatrician at the National Cancer Institute in Bethesda, Md. Water that spreads disease makes feeding with formula a dangerous option in some areas, he says.

Moreover, women in rural areas who bottle-feed a baby are sometimes suspected of having AIDS and then driven out of their village, says pediatrician Mary Glenn Fowler of the Centers for Disease Control and Prevention in Atlanta.

At present, the World Health Organization directs health workers to inform pregnant women of HIV-transmission risks and recommend formula where safe water is available.

The new findings “are certainly of interest and are provocative,” Fowler says. But scientists need to look at other studies for evidence that breast-feeding is really at fault. Although the U.S.-Kenyan researchers assigned the women to groups randomly, the bottle-feeding group seemed to contain slightly healthier women, she says.

Kreiss says, however, that her team’s findings might shift the balance further toward bottle-feeding when a mother carries HIV.

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