Breast-Feeding Past 6 Months Lowers Risk for HIV Transmission

Ricki Lewis, PhD

April 27, 2012

April 27, 2012 — Breast-feeding beyond 6 months when mother or infant is taking antiretrovirals (ARVs) can prevent HIV transmission, according to results from the Breastfeeding, Antiretrovirals, and Nutrition (BAN) trial published online April 26 in The Lancet.

Before 2010, the World Health Organization (WHO) and other public health agencies recommended ceasing breast-feeding for HIV-positive mothers in resource-poor countries at or before 6 months to balance the benefits of breast-feeding with the risk of transmitting HIV in milk. However, the newly reported BAN results indicate that once breast-feeding ceases at 6 months, risk for HIV transmission actually increases. In response to this and other studies, WHO guidelines now recommend that HIV-infected mothers of uninfected infants breast-feed for the first year.

Denise J. Jamieson, MD, from the US Centers for Disease Control and Prevention in Atlanta, and the BAN study team randomly assigned mother-infant pairs in Malawi to 3 groups: maternal triple ARVs, infant nevirapine, or no extended postnatal ARVs (controls). Infants were tested for HIV at birth and 2, 12, 28, and 48 weeks. Those infected by 2 weeks were released from the study and treated, as were mothers who progressed to AIDS or had plunging T-cell counts.

Women were instructed to wean between 24 and 28 weeks. At 32 weeks, most of the women in the intervention groups (96%) and in the control group (88%) reported having ceased breast-feeding.

As expected, at 28 weeks, pairs in which 1 member received ARVs had lower incidence of HIV infection than controls. Of the 676 mother-infant pairs in which the mothers took ARVs, 30 infants contracted HIV between 2 and 48 weeks. Of the 680 mother-infant pairs in which infants took nevirapine daily, 25 infants became infected. Of the 542 controls, 38 infants became infected.

"The cumulative risk of HIV-1 transmission by 48 weeks was significantly higher in the control group (7%, 95% CI [confidence interval] 5-9) than in the maternal-antiretroviral (4%, 3-6 p=0.0273) or the infant-nevirapine (4%, 2-5; p=0.0027) groups," the researchers write.

The research team collected data from 2004 to 2010. In 2008, noting the increased rate of HIV transmission in the controls, a data safety monitoring board at the National Institute of Allergy and Infectious Diseases recommended that all participants be assigned to an intervention group.

Assessing HIV infection after 28 weeks, when breast-feeding stopped, was revealing: 30% of the infections occurred during that period. Nine were in the maternal-ARV group, 13 in the infant-nevirapine group, and 6 in the control group.

Moreover, adverse events were more frequent during the postweaning period from 29 to 48 weeks, including diarrhea, impaired growth, malaria, tuberculosis, and death.

"The finding that mortality after 28 weeks was significantly higher than before this point (0.120 vs 0.065 per 100 person-weeks; p=0.0070) is cause for grave concern, because mortality rates should decrease with infant age," write Louise Kuhn, MD, Gertrude H. Sergievsky Center, College of Physicians and Surgeons, and Department of Epidemiology, Mailman School of Public Health, Columbia University, New York City, and Hoosen M. Coovadia, MD, University of Witwatersrand, Johannesburg, South Africa, and University of KwaZulu-Natal, Durban, South Africa, in an accompanying editorial.

A limitation of the study was the inability to draw conclusions about increased risk for adverse events in infants aged 6 to 12 months without also considering a group that continues breast-feeding.

Despite that limitation, Dr. Kuhn and Dr. Coovadia conclude that "[e]arly weaning is neither effective nor safe as an HIV prevention strategy."

Two coauthors received lecture fees from Abbott Laboratories. Another coauthor received free diagnostic kits from Abbott, Roche, Gen-Probe, IQuum, and Perkin-Elmer. The University of North Carolina received grant support from Abbott and GlaxoSmithKline. Dr. Kuhn and Dr. Coovadia have disclosed no relevant financial relationships.

Lancet. Published online April 26, 2012. Abstract Editorial

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