The rate of MTCT of HIV through breastfeeding can be as high as 0.7 percent per month.¹²⁹ In breastfeeding populations, 30 to 50 percent of MTCT is attributable to breastfeeding.¹³⁰ Although the U.S. Centers for Disease Control and Prevention has recommended since 1986 that women with HIV infection avoid breastfeeding, ¹³¹ breastfeeding is heavily implicated in fueling ongoing vertical transmission in resource-poor settings. The Petra study (in which AZT and 3TC were given during pregnancy only) revealed that most of the impact of preventive ART was negated when infants breastfed for 18 months, with comparable rates of transmission among interventions and placebo. ¹³² Risk of transmission via breastmilk has been found to be dependent on factors such as maternal viral load, maternal immune status, and infant feeding patterns, as well as by the presence of infant oral candidiasis or maternal breast pathologies such as mastitis or fissure. ^133–135

Debate over breastfeeding is especially fierce with regard to resource-poor settings, where the availability of infant formula and potable water is limited. However, obtaining formula and improving water sources is less complicated than administering lifelong care to HIV-infected infants. The provision of clean water also has a positive impact on the health of the mother, the family, and the community at large. We believe that the provision of clean water and aggressive diarrheal prevention is a critical cornerstone of linking HIV programs to evidence-based primary care. Similarly, the medical management of diarrheal diseases and close monitoring of growth and nutritional status is central to all child survival programs, whether or not infants have HIV. Given these considerations, recommending formula-feeding for infants born to HIV-infected mothers makes sense both practically and ethically.

While we strongly recommend that HIV-infected women not breastfeed their infants, we recognize that certain circumstances, such as fear of HIV status disclosure or unmitigable lack of access to potable water, may result in women continuing to breastfeed. As part of comprehensive HIV care, evaluation of the social and economic barriers that might lead to such a decision is encouraged.

UNICEF and other organizations recommend exclusive breast-feeding for six months, as some studies have demonstrated increased MTCT through mixed (i.e., breast and formula) feeding. However, studies have found that 75 percent of HIV infections from breastfeeding occurred during the first six months.¹³⁶ In addition, if early weaning is indeed promoted and nutritional supplementation is not provided, the infant is also at high risk for diarrhea and kwashiorkor.

In our 11 years of experience in providing infant formula, fewer than five percent of women have elected to breastfeed. For women who choose to breastfeed, weaning at six months is encouraged and nutritional support is given during the weaning period. Because malnutrition, mastitis, and breast lesions are all associated with increased risk of HIV transmission through breast milk, a multivitamin supplement (containing vitamins B, C, and E) as well as basic instructions on the prevention of mastitis and breast lesions should be provided to all breast-feeding women.^137,138 Single-dose NVP for the mother during labor and for the infant within 72 hours of birth has been associated with a sustained reduction in the transmission of HIV in breastfed babies through 18 months of age.¹³⁹ Studies are currently ongoing to determine if triple-drug maternal ART can reduce the risk of viral transmission to infants who continue to breastfeed.