Breast milk

The first evidence that HIV could be transmitted via breast milk  was a case report of the child of a previously HIV-negative woman who was delivered by Caesarean section. Because of blood loss from the operation, the mother was given a blood transfusion after the delivery. The baby was breastfed for six weeks. Later, it was discovered that a unit of the transfused blood had been contaminated with HIV. The mother and her infant were subsequently found to have both become infected.1

One study of pooled data from nine studies of over 4000 children born to HIV-positive mothers in high-prevalence countries found that after a year of breast-feeding, 7% contracted HIV infection.2

The process of HIV transmission during breastfeeding is poorly understood. However, HIV has been detected in breast milk and animal studies suggest that HIV can cross mucosal tissue in the mouth and upper gastrointestinal tract to infect neonates. High viral loads and low CD4 cell counts have been highly associated with transmission, as these may lead to higher viral loads in the breast milk.3 4 Moreover, recent study findings show that treatment of HIV-positive breastfeeding mothers with antiretroviral therapy results in reduced viral loads in breast milk, as well as drug levels in breast milk that may prevent HIV transmission.5 6

Both British and United States guidelines recommend that HIV-positive women should refrain from breastfeeding and use formula feed instead.

However in the absence of a sanitary water supply, replacement feeding in resource-limited settings leads to unacceptably high rates of infant mortality among HIV-exposed children from gastrointestinal illness and the surviving infants become weak and malnourished.

Breast milk and sex

Taking breast milk in the mouth can occur during sexual activity, and there is some potential for transmission, although there are no documented cases of HIV transmission through this route.


  1. Ziegler JB et al. Postnatal transmission of AIDS-associated retrovirus from mother to infant. Lancet 1: 896-898, 1985
  2. The Breastfeeding and HIV International Transmission Study Group The late postnatal transmission of HIV-1 in breastfed children: An individual patient data meta-analysis J Infect Dis 189: 2154-2166, 2004
  3. Pillay K et al. Cell-free virus in breast milk of HIV-1-seropositive women. J Acquir Immune Defic Syndr 24: 330-336, 2000
  4. Rousseau CM et al. Longitudinal analysis of HIV type-1 RNA in breast milk and its relationship to infant infection and maternal disease. J Infect Dis 187: 741-46, 2003
  5. Giuliano M et al. Triple antiretroviral prophylaxis administered during pregnancy and after delivery significantly reduces breast milk viral load a study within the drug resource enhancement against AIDS and malnutrition program. J Acquir Immune Defic Syndr 44: 286-291, 2007
  6. Kilewo C et al. Prevention of mother to child transmission of HIV-1 through breastfeeding by treating mothers prophylactically with triple antiretroviral therapy in Dar es Salaam, Tanzania – the MITRA Plus study. Fourth International AIDS Society Conference on HIV Treatment and Pathogenesis, Sydney, abstract TuAX101, 2007
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