Aspects of evaluation and care that are specific to pregnant women with HIV infection are summarized in Table 1. For women receiving protease-inhibitor therapy, 50-g glucose-load testing may be considered early in pregnancy to screen for glucose intolerance, with a second test at 24 to 28 weeks of gestation if the initial result is normal. Pregnant women receiving methadone in whom regimens containing nevirapine, efavirenz, or any protease inhibitor except indinavir are initiated should be monitored for signs and symptoms of drug withdrawal, since these agents have the potential to decrease methadone levels.
The schedule of testing for toxic effects of antiretroviral drugs depends on which drugs are chosen. In general, frequent evaluation (every two to four weeks) for new symptoms and laboratory abnormalities is indicated during the first one to two months of therapy, with less frequent testing thereafter. The optimal schedule of testing for the early diagnosis of antiretroviral-induced hepatic toxicity or lactic acidosis has not been determined, but one approach would be to evaluate hepatic function and electrolytes monthly during the third trimester and whenever new symptoms occur. HIV RNA levels should be monitored as in nonpregnant adults — that is, 4 weeks after a change or initiation of therapy, then monthly until undetectable, then every 3 months while therapy remains stable, and at 34 to 36 weeks of gestation for the planning of delivery. CD4+ lymphocyte counts should be evaluated every three months. Although the percentage of CD4+ lymphocytes is less subject to variation during pregnancy than the absolute count, most clinicians use treatment guidelines that are based on absolute counts; thus, absolute counts may be used in pregnant women as in nonpregnant adults.
Counseling with regard to the options for prenatal diagnosis is required for HIV-infected pregnant women. Although screening for serum markers or ultrasonographic examination may enhance the risk assessment, only invasive testing with fetal karyotyping can rule out chromosomal abnormalities. It is unclear whether invasive procedures for prenatal diagnosis carry a risk of HIV transmission. An increase by a factor of two to four in the risk of HIV transmission related to amniocentesis or other invasive procedures has been reported among untreated women. Invasive testing has not been identified as a specific risk factor for transmission in cohort studies performed since antiretroviral therapy has become standard, but the use of amniocentesis among HIV-infected women is uncommon, and the use of chorionic-villus sampling is rare. If a pregnant woman would not undergo amniocentesis after a positive result on serum or nuchal translucency screening, then such screening may be more anxiety-provoking than helpful. If an invasive prenatal procedure is planned for an HIV-infected woman, she should be receiving optimal antiretroviral therapy and have undetectable HIV RNA before the procedure.
The potential mode of delivery should be discussed throughout the pregnancy, and the final decision should be based on the HIV RNA level at 34 to 36 weeks of gestation. Infusion of zidovudine should be begun as soon as possible after the onset of labor or the rupture of the membranes (or at least three hours before a scheduled cesarean delivery), at a dose of 2 mg per kilogram of body weight given over the course of one hour, followed by a continuous infusion of 1 mg per kilogram per hour until delivery. The use of other antiretroviral medications should be continued on schedule during labor or preoperatively. Stavudine may antagonize the effects of zidovudine and should therefore be given orally without zidovudine or discontinued before intravenous zidovudine is administered.
Artificially induced rupture of the membranes should be avoided, and the interval between rupture and delivery should be minimized by augmenting labor as needed after spontaneous rupture has occurred. Fetal-scalp electrodes, scalp blood sampling, the use of instruments to assist delivery, and other procedures that might be traumatic to the infant should be avoided. Avoidance of episiotomy may decrease the exposure of the infant to maternal blood. Midazolam and ergot preparations should not be used in women receiving protease inhibitors, efavirenz, or delavirdine, because their metabolism may be delayed by such antiretroviral drugs. The infant should be washed before any blood is drawn or any injections or other invasive procedures are performed.
HIV-infected women require additional counseling and support during the postpartum period. In industrialized countries, breast-feeding by HIV-infected women is not recommended because it is associated with an additional 15 to 20 percent risk of transmission of HIV. Among women in whom antiretroviral therapy is continued after delivery, measures to enhance adherence to the regimen may be needed because of the demands of newborn care, the loss of the incentive of preventing transmission, and postpartum depression. Adherence may be improved by simplifying the regimen, explaining again the consequences of nonadherence, using aids such as daily pill boxes or pagers, recruiting family and friends for support, and using support groups. Additional psychosocial support is needed while the infant’s HIV status is being determined and afterward if the infant is found to be infected with HIV.
Options for contraceptive methods should be discussed during pregnancy and the need for condom use should be emphasized. If a woman elects to use additional methods, interactions with other therapies must be considered. Estradiol levels from oral contraceptives are reduced by nevirapine, ritonavir, nelfinavir, rifampin, rifabutin, and possibly amprenavir, which may reduce the contraceptive efficacy. Interactions between medroxyprogesterone acetate and antiretroviral drugs are under study, but this agent is a reasonable choice. Intrauterine contraceptive devices may be offered to HIV-infected women who have a low risk of sexually transmitted infections and do not have severe immune suppression. The appropriate care for infants born to HIV-infected women is described in Table 1. Although the provision of early access to prenatal care for all women and universal voluntary HIV testing during pregnancy would allow for interventions that can improve maternal health and reduce HIV transmission, the ultimate goal must be primary prevention of HIV infection in women.
From the Pediatric, Adolescent, and Maternal AIDS Branch, Center for Research on Mothers and Children, National Institute of Child Health and Human Development, Bethesda, Md.
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D. Heather Watts, M.D.
The New England Journal of Medicine