Most common cause of HIV infection in infant is:
**Core Concept**
Mother-to-child transmission (MTCT) of HIV is the primary mode of infection in infants. This occurs during pregnancy, labor, delivery, or breastfeeding, and is influenced by maternal viral load, mode of delivery, and antiretroviral therapy (ART) use.
**Why the Correct Answer is Right**
The most common cause of HIV infection in infants is vertical transmission from an infected mother during pregnancy or childbirth. This can happen through the placenta, during labor, or through breastfeeding. The risk of transmission is highest when the mother's viral load is high, and can be significantly reduced with the use of antiretroviral therapy (ART) and elective cesarean delivery before the onset of labor and before the rupture of membranes.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified; however, it's likely to be a distractor like maternal HIV testing or other risk factors.
**Option B:** This option is also not specified; however, it could be a distractor like congenital syphilis or other congenital infections.
**Option C:** This option is also not specified; however, it could be a distractor like blood transfusion or other modes of transmission.
**Clinical Pearl / High-Yield Fact**
The risk of HIV transmission from an infected mother to her child can be as high as 20-30% if left untreated. However, with the use of ART and other preventive measures, the risk can be reduced to less than 2%.
**Correct Answer: C. Mother-to-child transmission.