Replacement feeding is the only 100% effective way to prevent mother-to-child transmission of HIV after birth. This benefit, however, must be weighed against practical difficulties and the risk from other illnesses, which is increased by not breastfeeding. According to WHO, the necessary conditions for replacement feeding can be summarised as follows.
Acceptability: Breastfeeding is the norm in most cultures, and is generally encouraged by health workers. By choosing not to breastfeed, a mother risks revealing that she is HIV positive, and becoming a target for stigma and discrimination. She must be able to cope with this problem and resist pressure from friends and relatives to breastfeed.
“Many women/couples prepare to try out formula food after receiving counselling on the possibilities of breast milk infecting the infant after birth and information on formula feeds. But the problem crops up when the woman is back home with the extended family who are not aware of the HIV status of the mother or the couple.”
Feasibility: A mother who chooses replacement feeding must have adequate time, knowledge, skills and other resources to prepare the replacement food and feed her baby up to twelve times in 24 hours. Boiling water over a charcoal stove, for instance, can take up to fifteen minutes per feed. Unless refrigerated, prepared formula becomes unsafe after just two hours. It is better to feed with a cup rather than a bottle because cups are easier to clean, and because cup feeding promotes greater interaction between the mother and her baby.
Affordability: Someone has to pay for the ingredients, fuel, water and other equipment needed for replacement feeding. In some countries, the cost of infant formula alone is similar to the minimum urban wage and, unless heavily subsidised, is well beyond the reach of most families.
Sustainability: Feeding an infant for the first six months of life requires around 20 kg of formula and regular access to water. Even a brief disruption in supplies may have serious health implications.
Safety: Replacement food should be nutritionally sound and free from germs. The water it is mixed with should be boiled, and utensils should be cleaned (preferably boiled) before each use. This means the mother must have access to a reliable supply of safe water and fuel.
Of the five conditions for replacement feeding, safety is often the most critical. Several studies of babies born to HIV-positive mothers in developing countries have tried to determine which type of feeding results in a lower death rate or a higher rate of “HIV-free survival” (the proportion of babies left alive and HIV-negative). These include:
A randomised trial in Kenya (2001), which concluded that, “infants assigned to be formula fed or breastfed had similar mortality rates and incidence of diarrhea and pneumonia during the first 2 years of life. However, HIV-1-free survival at 2 years was significantly higher in the formula arm.”13
The non-randomised Diatrame Plus study in Côte d’Ivoire (2006), which found “no difference in two-year rates of adverse health outcomes between early weaned breastfed and formula-fed children,” and “mortality rates did not differ significantly between these two groups.”14
The randomised Mashi Study in Botswana (2006), which found that, “Breastfeeding with zidovudine prophylaxis was not as effective as formula feeding in preventing postnatal HIV transmission, but was associated with a lower mortality rate at 7 months. Both strategies had comparable HIV-free survival at 18 months.”15 Rates of HIV-free survival were also similar at 24 months.16
A pooled analysis of African studies (2004), which found, “Mortality did not differ significantly between ever-breastfed and never-breastfed children [born to HIV-positive mothers], with or without allowance for child infection status.”17
Outcomes depend on many local factors, including the conditions in which replacement feeding is provided, and whether breastfeeding is exclusive or mixed (see below). It is worth noting that mothers enrolled in trials usually have access to potable water, extensive education on safe preparation of formula, a reliable supply of formula, and medical care for their infants.
Taken together, these studies demonstrate that replacement feeding can be beneficial, but certainly not in all situations. WHO recommends that counsellors talk with women and assess their individual circumstances before giving guidance about the risks and benefits of different modes of feeding. It is especially important to establish whether the mother has access to clean water and fuel, and whether she has disclosed her HIV status to her partner or family members.
Support for mothers who choose replacement feeding
To prepare replacement foods and feed them to a baby several times per day for many months is challenging, even in the best of circumstances. Mothers who choose replacement feeding need help to succeed. At the bare minimum, this means teaching them how to prepare the food properly, and then asking them to give a demonstration to ensure they understand. Counsellors must emphasise the need for sterile equipment and correct dilution, and the dangers of keeping prepared formula for long periods at room temperature. Mothers should also be taught how to prevent breast engorgement (preferably without using drugs), and how to recognise and treat dehydration.
It might seem obvious that clinics should offer HIV positive mothers a free supply of infant formula. However infant formula is expensive to buy and difficult to distribute. In some settings, providing formula may divert resources from other measures to avert mother-to-child transmission, such as HIV testing or preventive drugs.
The United Nations Children's Fund, UNICEF, began distributing free infant formula to governments in 1998, to be given to HIV positive mothers who wanted to avoid breastfeeding but could not afford to do so. UNICEF decided to abandon the scheme four years later after deciding it was unhelpful. The charity found that formula was often given to women who were incapable of preparing it safely, while most of those who had the resources to practise safe replacement feeding could also afford to purchase formula. Furthermore UNICEF was concerned that the provision of free formula was leading to “spillover” .