Antiretroviral therapy

The use of AZT (zidovudine) during the second and third trimester in pregnant women and in infants during the first six weeks of life, in the absence of breastfeeding, can reduce mother-to-child transmission of HIV by two-thirds (Connor et al., 1994). A "short course" regimen of AZT (after 36 weeks gestation and without the neonatal component), combined with formula feeding, has recently been shown in Thailand to reduce mother-to-child HIV transmission by half (Centers for Disease Control, 1998). The latter approach may be more feasible where women present late for prenatal care, or where health service resources are limited. Further reductions in mother-to-child HIV transmission may be possible with the use of a combination of antiretroviral drugs (Bryson, 1996), which are currently being evaluated in clinical trials in both breastfeeding and non-breastfeeding populations (Fowler, 1997).

The effectiveness of AZT in reducing mother-to-child transmission has been demonstrated only in non-breastfed infants. It is currently not known to what extent infants who have escaped infection during pregnancy and delivery, following prophylactic therapy in their mothers with AZT, are at risk of becoming infected subsequently through breastfeeding. However, it is likely that antiretroviral therapy around the time of delivery will not be as effective if the infant is then exposed through breastfeeding. Since many HIV-infected mothers may face obstacles to replacement feeding - for example stigma, affordability, risk to the infant of other infections and malnutrition - the effectiveness of antiretroviral treatment of breastfeeding mothers/or breastfed infants, with and without a postnatal treatment component, is an important research question. Several trials are under way, in populations where breastfeeding is the norm, to evaluate various AZT regimens, combination therapy using two antiretrovirals (AZT with 3TC), and Nevirapine (Fowler, 1997). Results of these and other trials will be available by mid-1999. It is important for this information to be available before policies are adopted which introduce antiretroviral therapy to reduce the risk of mother-to-child transmission in situations where infant feeding choices are limited.