Normally breastfeeding is by far the best way to feed an infant, especially in the developing world. It is the simplest and most efficient way to deliver good nutrition to the infant. Breastmilk contains maternal antibodies and other factors that may protect infants from community acquired infections. Breastfeeding can also benefit the mother by delaying the return to fertility, which helps with child spacing and reduces the burden of childbearing.

However, when the mother is infected with HIV, breastfeeding can transmit the virus to her child. That risk can be great in countries where prolonged breastfeeding is common, accounting for 42% of HIV infections in infants and young children in Africa according to a major meta-analysis of breastfeeding studies.^[1] Overall, an estimated 5 to 20% of infants born to HIV-infected mothers are infected postpartum via breastfeeding.

In the developed world, both British and United States guidelines recommend that HIV-positive women should refrain from breastfeeding and use formula feed. Elsewhere, the World Health Organization (WHO) and the United Nations Children’s Funds (UNICEF) also recommend that HIV-infected mothers completely avoid breastfeeding when replacement feeding is acceptable, feasible, affordable, sustainable, and safe (AFASS).

With the exception, perhaps, of studies that have enrolled mothers who live in urban settings with clean tap water running into their homes, most studies have reported that replacement feeding in resource limited settings is leading to unacceptably high rates of infant mortality among HIV-exposed children and that the surviving infants wind up weak and malnourished.

When local circumstances and the risks of replacement feeding, including the prevalence of community-acquired infections and malnutrition, are taken into account, formula feeding becomes a very limited option. According to a WHO meta-analysis, in the poorest countries, children who are not breastfed during the first two months of life are six times more likely to die from infectious diseases.^[2]

Much of the risk associated with breastfeeding is actually due to mixed feeding, that is, breastfeeding combined with giving the infant solid foods or other liquids such as formula, other animal milk, tea, or juice. In the most recent of these studies, when infants were exclusively breastfed, only 1% became infected at six months compared to 4% who received mixed feeding.

However, there are significant challenges in getting women to choose formula feeding, or exclusive breastfeeding with early weaning in settings where these are not common infant feeding practises and where either choice can stigmatise the women and her infant.

To minimise the risk of mixed-feeding, mothers who chose to exclusively breastfeed were often encouraged to wean as early as possible (within two to four months of birth), only to be confronted again with the difficult question of what to feed their infant. The results of at least four different studies presented in 2007 showed that abrupt and early weaning of HIV-exposed, but negative, infants in sub-Saharan Africa was associated with high rates of severe diarrhoea and gastroenteritis that, in some cases, led to death.

In three of those studies, morbidity rates were significantly higher than seen in historical controls. This was despite the fact that virtually all the infants were receiving co-trimoxazole prophylaxis, a factor that should have improved outcomes. Early weaning was associated with an increased rate of diarrhoea and researchers noted that improved instruction on hygiene, sanitation, and water purification during pre-weaning counselling is necessary. Additionally, that infants being weaned early need be more closely monitored, and in most settings, offered quality nutritional support.

However, many have recommended reassessment of current WHO and Ministry of Health recommendations that  encourage early breastfeeding cessation among HIV-infected women. Additionally, research on the effects of early weaning revealed that the practise itself increases the risk of transmission by dramatically increasing HIV levels in the breast milk.

Researchers are trying to gain a better understanding of the viral dynamics of HIV in breastmilk and are working to identify factors and interventions that can decrease the risk of transmitting HIV through breastmilk.