2. Mother-to-child transmission of HIV: an overview

· HIV can be passed from mother to child in the womb, during childbirth or through breastfeeding.

· In developing countries with no interventions, over a third of HIV-positive mothers will generally pass HIV infection on to their babies.

· Avoiding breastfeeding can cut the risk of transmission to between 20% and 25%.

· The provision of the antiretroviral drug ZDV (or zidovudine) for the last four weeks of pregnancy and during labour can further cut the risk of transmission to under 10% if women also avoid breastfeeding. Feasibility and effectiveness of this type of therapy, known as “short course ZDV”, are being tested in developing countries where breastfeeding is the norm. It is important also to note that a short course of antiretroviral drugs during pregnancy, while increasing the chance that she will give birth to an uninfected baby, does no harm to the health of an HIV-positive woman. The only possible risk is anaemia. But anyone taking antiretroviral drugs for HIV should be screened for this condition in advance, and treated for it if necessary. Concern is sometimes expressed that the strategy might encourage the development of drug-resistant strains of HIV. However, the risk of resistance developing is minimal with such a short period of drug use.

· Other, even shorter antiretroviral regimens are being tested. Preliminary results show that therapy beginning at labour and given for one week after delivery may also be effective in cutting transmission of HIV from mother to infant.

· A longer and more complex course of ZDV known as “ACTG 076” can reduce mother-to-child transmission of HIV to around 5% in women who do not breastfeed. This therapy is common in industrialized countries. However, it is too expensive and difficult to administer for routine use in developing countries where both fertility and HIV prevalence are high and resources are limited.

· Delivery by Caesarean section in women on AGTG 076 who do not breastfeed has been shown to reduce the risk of transmission to about 1%. This procedure is difficult to undertake safely where health infrastructure is limited. The risks associated with sepsis following this operation are greater in HIV-infected than in HIV-negative women.

· Vitamin supplementation, cleansing of the birth canal and avoiding invasive procedures during delivery may all help reduce the risk of transmission of HIV from mother to child. Since the presence of other STDs may increase the risk of a woman passing HIV infection on to her child, screening and treatment of STDs other than HIV may also reduce transmission rates. Research on these interventions continues. However, they are relatively cheap and beneficial to all women regardless of their HIV status.