What are the main routes through which HIV can be transmitted from mother to child?

The correct answer highlights two primary pathways for the transmission of HIV from mother to child: across the placenta during pregnancy (in utero) and through breastfeeding after birth.

During pregnancy, the virus can cross the placenta and infect the developing fetus. This can occur at any stage of pregnancy, although the risk of transmission varies; it is generally higher during the later stages. This mode of transmission can result in the child being born with HIV.

Breastfeeding is another significant route of transmission. HIV can be present in breast milk, and an infant who nurses from an HIV-positive mother is at risk of acquiring the virus. The risk is particularly pronounced if the mother has a high viral load or if the breastfeeding occurs while the mother has open sores or conditions that might cause breast tissue trauma.

Combining these two modes of transmission provides a comprehensive view of how HIV can be passed from an HIV-positive mother to her child, underlining the importance of monitoring and interventions during both pregnancy and the postpartum period to mitigate these risks.