Which antiretroviral agent is used intrapartum to prevent mother-to-child transmission of HIV?

• A. Abacavir
• B. Efavirenz
• C. Zidovudine
• D. Lamivudine

Answer: (C)

Intrapartum antiretroviral prophylaxis aims to reduce the risk of HIV transmission during delivery by suppressing viral replication in the fetus at the moment of birth. Zidovudine, given intravenously during labor, is the classic choice for this window because it crosses the placenta and inhibits reverse transcriptase, lowering the amount of virus the newborn is exposed to during delivery. This approach has been shown to significantly reduce mother-to-child transmission rates. After birth, the newborn typically receives zidovudine prophylaxis as well.

Other agents are used in long-term maternal ART regimens, but zidovudine is the standard intrapartum prophylactic drug. For example, efavirenz is generally avoided in pregnancy due to potential teratogenic effects, while abacavir and lamivudine are valuable parts of ART but not the primary intrapartum prophylaxis.