Most cases of HIV transmission from the mother to the infant occur at which time?

• A. Antenatal transmission due to invasive procedures
• B. At the time of delivery
• C. Postnatally from breastfeeding
• D. Across the entire pregnancy equally

Answer: (B)

Transmission of HIV from mother to infant can happen before birth, during the birth process, or after birth through breast milk. The highest risk window is the delivery period because the infant is exposed directly to maternal blood and secretions as it passes through the birth canal. In utero transmission can occur but is less common than intrapartum transmission, and postnatal transmission via breastfeeding is possible but typically lower than the peripartum risk when antiretroviral therapy is used for both mother and infant. Therefore, most cases occur at the time of delivery.