The commonest route of transmission of HIV from the mother to the baby is –
**Core Concept**
The transmission of HIV from mother to child (MTCT) is a significant concern in obstetrics and pediatrics. It occurs during pregnancy, labor, delivery, or breastfeeding, and the likelihood of transmission varies depending on the stage of pregnancy and the mode of delivery.
**Why the Correct Answer is Right**
The most common route of HIV transmission from mother to child is during the intrapartum period, specifically during vaginal delivery. This is because the baby is exposed to the mother's blood and vaginal secretions, which contain high concentrations of HIV particles. The risk of transmission is higher if the mother has a high viral load, if she is in labor for an extended period, or if the baby is delivered vaginally.
**Why Each Wrong Option is Incorrect**
**Option A:** Intrauterine transmission occurs when the baby is infected in the womb, but it is less common than intrapartum transmission.
**Option B:** Breastfeeding transmission occurs when the baby is infected through breast milk, but it is not the most common route of transmission.
**Option C:** Fetal transfusion occurs when the baby receives infected blood from the mother's placenta, but it is a rare mode of transmission.
**Clinical Pearl / High-Yield Fact**
The risk of MTCT can be significantly reduced with the use of antiretroviral therapy (ART) in the mother, elective cesarean delivery before the onset of labor, and avoiding breastfeeding.
**Correct Answer: C. Intrapartum transmission is the commonest route of HIV from the mother to the baby.**