**Question:** Regarding HIV transmission to foetus all are true except –a) > 50% risk of transmission to foetusb) Can present as failure to thrivec) Greatest risk of transmission of in perinatal periodd) Cannot be diagnosed

**Core Concept:** HIV (Human Immunodeficiency Virus) transmission during pregnancy, childbirth, or breastfeeding. HIV infection poses a risk to the unborn child, who can acquire the virus through the mother's blood and bodily fluids during these critical stages of pregnancy, childbirth, and breastfeeding.

**Why the Correct Answer is Right:** Option D ("Cannot be diagnosed") is incorrect because there are diagnostic tools available to identify HIV infection in pregnant women. These include HIV screening tests, such as enzyme-linked immunosorbent assay (ELISA) and Western blot, which can accurately detect the virus in blood samples.

**Why Each Wrong Option is Incorrect:**

A. > 50% risk of transmission to foetus: While the risk of HIV transmission to the foetus during childbirth or breastfeeding is high (around 25-45%), the statement that it is "> 50%" is incorrect.

B. Can present as failure to thrive: HIV infection can present with various manifestations, including failure to thrive, but this is not specific to HIV transmission alone. Failure to thrive can be due to several causes, unrelated to HIV transmission.

C. Greatest risk of transmission of in perinatal period: While the perinatal period contains a higher risk of transmission than other stages, the statement that it is "the greatest risk" is an overgeneralization. HIV transmission can occur during all stages of pregnancy, childbirth, and breastfeeding.

**Clinical Pearl:** HIV testing during pregnancy is crucial to identify infected mothers and provide appropriate antiretroviral therapy (ART) prophylaxis to reduce the risk of perinatal transmission. Additionally, avoiding breastfeeding is a proven method to prevent HIV transmission to the infant. A combination of ART therapy and appropriate preventive measures can significantly reduce the risk of perinatal HIV transmission.