Prevalence of the T215Y mutation in human immunodeficiency virus type 1-infected pregnant women in a New York cohort, 1995--1999

Human immunodeficiency virus infection and pregnancy

Human immunodeficiency virus infection profoundly affects the medical community and is spreading rapidly in women of childbearing age worldwide. Transmission of HIV from mother to child can occur in utero, during labor, or after delivery through breast-feeding. Most of the infants are infected during delivery. We focus on the factors affecting the transmission of HIV, diagnostic and resistance tests, strategies to prevent mother-to-child transmission with special reference to mode of delivery, infant feeding, and use of antiretroviral therapy. The risk of infection for the infant can be decreased by reducing maternal viral load, by elective cesarean delivery, and by avoidance of breast-feeding. The efficacy of antiretroviral treatment should be balanced against the possibility of embryonic or fetal toxicity. The choice of therapy should be based on the woman's treatment history, the clinical status, and the available prognostic markers, which are related to the progression of disease in the mother and the risk of mother-to-child transmission HIV transmission.

Antiretroviral Therapy for Prevention of Mother-to-Child HIV Transmission

Administration of potent antiretroviral combination therapy in the second and third trimester of pregnancy and during delivery, and for 6 weeks postpartum to the infant, may reduce HIV transmission from the mother to the child to <2% in formula-fed infants. In resource-constrained settings where women have limited access to antenatal care, use of shorter and more practical regimens, including nucleoside reverse transcriptase inhibitors (NRTIs) and/or non-NRTIs (NNRTIs) commenced later in pregnancy, has demonstrated efficacies ranging from 18% to 70% in breast- and bottle-fed populations. Because shorter interventions include regimens such as single-dose nevirapine or zidovudine monotherapy, which do not provide maximal suppression of viral replication, emergence of resistant mutations in mother and infant occurs frequently, primarily after exposure to drugs with low genetic barriers (i.e. those requiring only one genotypic mutation to develop resistance), such as nevirapine. Different studies have reported nevirapine resistance rates ranging from 25% to 69% in mothers receiving single-dose nevirapine alone. Because NNRTI-based combinations of antiretroviral agents are recommended as first-line therapy in countries where single-dose nevirapine is the main option for preventing mother-to-child transmission of HIV, concerns have been raised as to whether single-dose nevirapine prophylaxis can compromise the efficacy of subsequent NNRTI-based antiretroviral therapy regimens. However, although some studies have shown that nevirapine exposure may impact on short-term virological outcome, the clinical relevance of nevirapine resistance remains unclear, especially in women who start treatment >6 months after delivery or in those who are not severely immunocompromised. Furthermore, studies have shown that adding short-course (up to 7 days) zidovudine or zidovudine/lamivudine prophylaxis after delivery may dramatically reduce the occurrence of nevirapine resistance in both mothers and infants. Until data are available that allow a better understanding of the relevance of antiretroviral drug resistance acquired as a result of mother-to-child HIV transmission prophylaxis, women and children who have previously received single- dose nevirapine as part of a mother-to-child transmission prevention strategy should be considered eligible for NNRTI-based regimens and should not be denied access to antiretroviral therapy.