Preventing Neonatal HIV

Abstract & Commentary

Synopsis: "Bloodless" c-sections may reduce HIV transmission.

Source: Towers CV, et al. A bloodless cesarean section and perinatal transmission of the human immunodeficiency virus. Am J Obstet Gynecol 1998;179:708-714.

While vertical transmission of hiv during pregnancy is common, neonates are also at high risk for infection at the time of delivery. Towers and colleagues examined whether a bloodless cesarean section (BCS), in which the infant was not exposed to any maternal blood or body fluids, could reduce the risk of HIV transmission.

A total of 53 infants delivered by BCS were compared with infants delivered by routine cesarean section or by vaginal delivery (n = 55). BCS resulted in a 75% risk reduction, with 5.7% of infants delivered by BCS compared with 20% of control subjects having evidence of HIV infection at 1 year (P = 0.02). Excluding infants born to mothers who received zidovudine during their pregnancy and/or peripartum, two of 32 (6.3%) infants in the BCS group vs. nine of 38 (23.7%) controls were HIV-infected (P = 0.04).

Comment by Carol A. Kemper, MD

A similar reduction in vertical HIV transmission using pre-parturition cesarean section (CS) was reported by German investigators at the 12th World AIDS Conference in Geneva. Only six of 124 (4.8%) children delivered by CS prior to the onset of labor had evidence of HIV infection at 6 months, compared with 21% of infants delivered vaginally and 17.5% delivered by CS at the time of parturition (P = 0.0013).1 Only one in 87 children whose mothers were both treated with zidovudine and delivered by pre-parturition CS acquired HIV (1.1%).

These data demonstrate that both the timing and the methodology of cesarean section can affect the frequency of neonatal acquisition of HIV infection. However, because the frequency of HIV infection in mothers who did not receive zidovudine but delivered by BCS was similar to those who received zidovudine but delivered vaginally, BCS may not offer a significant advantage over the use of zidovudine. Data is extent on whether the use of multiple antiretroviral agents in combination can further reduce the risk of vertical transmission without necessitating surgical intervention or compromising safety.

Current guidelines for HIV-infected pregnant women in the United States recommend that the therapeutic approach should be similar to that for HIV-infected women who are not pregnant, with the goal of treatment being complete virologic suppression.2 The role of protease inhibitors in this regard is still being investigated, although PIs were possibly associated with an increased risk of premature delivery in pilot studies. Preliminary pharmacokinetic and safety data suggest that nevirapine caused no adverse effects in mothers or their infants.3,4 Seventeen infants born to mothers treated with a combination of nevirapine, zidovudine, and a second nucleoside analog for a median of 20 weeks were HIV DNA PCR-negative at birth.4 On the other hand, a recent alert indicated that efavirenz resulted in fetal malformation in monkeys, although earlier research in rabbits and rats failed to demonstrate any significant toxicity. The drug has not been ruled-out for possible use in late pregnancy.

Despite the recent successes of medical management of HIV-infected pregnant women, surgical intervention may remain a valid option for mothers with high viral loads due to antiretroviral therapy failure or less than optimal compliance, or for those who present too late in their pregnancy for adequate medical intervention.

References

1. Shaefer A, et al. Influence of cesarean section before parturition and antiretroviral prophylaxis on the materno-fetal transmission of HIV. 12th World AIDS Conference, Geneva, 1998 (Abstract 12466); Conference Supplement, p. 7.

2. Public Health Service Task Force Recommendations for the Use of Antiretroviral Drugs in Pregnant Women Infected with HIV-1 for Maternal Health and for Red-ucing Perinatal HIV-1 Transmission in the United States. MMWR Morb Mortal Wkly Rep 1998;47:No. RR-2.

3. Mirochnik M, et al. Pharmacokinetics of nevirapine in human immunodeficiency virus type-1 infected pregnant women and their neonates. J Infect Dis 1998; 178:368-374.

4. Luzuriaga K, et al. 5th Conference on Retroviruses and Opportunistic Infections, Chicago, 1998. Abstract LB-12.