Introduction

Antiretroviral therapy can reduce the risk of mother-to-child transmission of HIV. This was first demonstrated with the publication of the ACTG 076 trial in 1994, in which AZT (zidovudine, Retrovir) reduced the risk of transmission by two-thirds when it was given by mouth to the mother during pregnancy, intravenously during labour, and by mouth to the infant for the first six weeks after childbirth.

Since that time, a number of major studies with antiretroviral drugs have been conducted in developed countries as well as resource-limited settings. These clinical trials have compared or added other antiretrovirals to AZT or nevirapine (Viramune), in breastfeeding and non-breastfeeding populations. They have investigated aspects such as the best time to start treatment for preventing transmission as well different approaches to treatment during labour or after childbirth. Recent studies have also explored ways to reduce the development of antiretroviral resistance associated with treatment to prevent mother-to-child transmission that could limit a mother's future treatment options.

Because of this research, treatment protocols (often called short courses) have been incrementally improved, to the point where the rate of mother-to-child transmission has been reduced to less than 4% in non-breastfeeding populations, even in resource-limited settings.

Evolution in the standard of antiretroviral therapy for people with HIV in the developed world has lead to widespread use of combination antiretroviral regimens in pregnancy, especially when the mother needs treatment for her own health. Not all treatment regimens have not been carefully studied in controlled clinical trials, although many large observational cohort studies show that antiretroviral drugs are generally safe. In addition, epidemiological data have confirmed that women on effective antiretroviral therapy are much less likely to transmit HIV to their infant during pregnancy and labour. When combined with elective Caesarean delivery, the rate of mother-to-child transmission can fall below 1% in developed countries.