What methods prevent HIV transmission in pregnancy?

Methods to Prevent HIV Transmission in Pregnancy

All HIV-infected pregnant women should receive combination antiretroviral therapy (cART) including zidovudine after the first trimester, with intravenous zidovudine during labor and 6 weeks of infant prophylaxis, plus scheduled cesarean delivery at 38 weeks if viral load remains >1,000 copies/mL. 1

Antiretroviral Therapy Regimens

Standard Combination Therapy

• Highly active antiretroviral therapy (HAART) should be initiated after the first trimester in treatment-naïve pregnant women, ideally containing zidovudine as a backbone component. 1
• The preferred regimen consists of dual nucleoside reverse transcriptase inhibitors (NRTIs) plus either an integrase strand transfer inhibitor or ritonavir-boosted protease inhibitor. 2
• Standard combination antiretroviral regimens should be offered to all pregnant women regardless of viral load, and are specifically recommended for those with HIV RNA >1,000 copies/mL. 3

Zidovudine-Based Prevention

• Zidovudine monotherapy reduced perinatal transmission by approximately two-thirds (from 25.5% to 8.3%) in the landmark PACTG 076 trial. 3, 1
• For women with HIV RNA <1,000 copies/mL who wish to limit fetal antiretroviral exposure, time-limited zidovudine during the second and third trimesters may be considered, though full combination therapy is preferred. 3
• Antiretroviral prophylaxis reduces transmission even in women with HIV RNA <1,000 copies/mL (1.0% transmission with therapy vs 9.8% without). 3

Abbreviated Regimens for Late Presenters

• Single-dose nevirapine (200 mg) at labor onset for the mother plus nevirapine (2 mg/kg) for the infant at 48 hours reduces transmission by approximately 50%. 3, 1
• Zidovudine plus lamivudine given orally during labor and for 1 week postpartum to both mother and infant is effective. 3
• Short antepartum/intrapartum zidovudine regimens reduced transmission by 50% in non-breastfeeding populations. 3
• Caution: Nevirapine should be used carefully in women with CD4 counts >250/mm³ due to severe hepatotoxicity risk. 1

Intrapartum Management

Zidovudine Infusion Protocol

• Continuous intravenous zidovudine infusion should begin 3 hours before scheduled cesarean delivery or at labor onset. 3, 1
• The infusion should continue throughout labor and delivery for all HIV-infected women. 1
• Other antiretroviral medications in the regimen should be continued on schedule as much as possible before and after surgery. 3

Scheduled Cesarean Delivery

• Elective cesarean section at 38 weeks gestation (before labor onset and membrane rupture) should be offered to women with HIV RNA >1,000 copies/mL at 34-36 weeks gestation. 3, 1
• Cesarean delivery reduces perinatal transmission by approximately 50% overall compared to vaginal delivery. 3
• A European randomized trial demonstrated benefit for both untreated women and those on antiretroviral therapy. 3
• Important caveat: Cesarean delivery carries increased maternal morbidity risks including higher postoperative infection rates, anesthesia complications, and surgical risks compared to vaginal delivery. 3

Interventions That Do NOT Work

• Vaginal disinfection during labor has not proven effective. 3
• Cleansing of the newborn alone has not proven effective. 3

Infant Prophylaxis

Standard Regimen

• Infants born to mothers who received adequate antenatal antiretroviral therapy should receive oral zidovudine for 6 weeks. 1, 4
• This 6-week neonatal zidovudine course is a critical component of the three-part PACTG 076 regimen. 3, 1

High-Risk Infant Regimen

• For infants born to mothers with no antiretroviral therapy before or during labor: either single-dose nevirapine (2 mg/kg) at birth PLUS zidovudine for 6 weeks, OR zidovudine alone for 6 weeks. 1
• The combination approach provides additional protection when maternal prophylaxis was inadequate. 1

Viral Load-Based Decision Algorithm

For Women with HIV RNA <1,000 copies/mL

• Continue current combination antiretroviral therapy through delivery. 3
• Vaginal delivery is reasonable if viral load remains suppressed near term. 3
• Maintain intravenous zidovudine during labor. 1

For Women with HIV RNA 1,000-10,000 copies/mL

• Transmission rates range from 1-12% (mean 5.7%) with zidovudine therapy alone. 3
• Scheduled cesarean delivery at 38 weeks should be strongly recommended to further reduce intrapartum transmission risk. 3

For Women with HIV RNA >10,000 copies/mL

• Transmission rates range from 9-29% (mean 12.6%) with zidovudine therapy. 3
• Scheduled cesarean delivery is essential and should be performed at 38 weeks with the full three-part zidovudine regimen. 3

For Women Starting Therapy in Third Trimester

• Even with appropriate viral response, if HIV RNA remains substantially >1,000 copies/mL at 36 weeks, scheduled cesarean delivery provides additional benefit. 3
• Continue combination therapy as viral suppression typically requires several weeks depending on baseline RNA level. 3

Additional Prevention Strategies

Breastfeeding Avoidance

• Breastfeeding is not recommended for HIV-infected women in resource-rich settings like the United States. 1
• Safe alternatives to breast milk eliminate this route of postnatal transmission. 3

Postpartum Maternal Considerations

• Evaluate the need for continued maternal antiretroviral therapy after delivery based on CD4 count, viral load, and clinical status. 1
• If discontinuing therapy postnatally (for women who received treatment solely for prevention), stop all drugs simultaneously to avoid resistance. 3
• For regimens containing drugs with long half-lives (like NNRTIs), consider continuing nucleoside analogues for 3-7 days after stopping the NNRTI to reduce resistance risk. 1

Efficacy of Combined Approaches

• With combined antiretroviral therapy (typically dual-NRTIs plus integrase inhibitor or boosted protease inhibitor), transmission rates can be reduced to <2% when mothers achieve undetectable viral loads. 2
• The addition of lamivudine to zidovudine plus lopinavir/ritonavir reduces time to achieve viral load <50 copies/mL, particularly crucial for women with high pretreatment viral loads who start therapy late. 5
• Maternal HIV viral load is the strongest predictor of perinatal transmission, making suppressive antiretroviral treatment the principal means of prevention. 2