## **Core Concept**
Vertical transmission of Hepatitis B refers to the transmission of the virus from mother to child during birth or in the perinatal period. This mode of transmission is a significant concern as it can lead to chronic Hepatitis B infection in the newborn. The risk of vertical transmission is influenced by several factors, including the mother's viral load.

## **Why the Correct Answer is Right**
The correct answer, , indicates that the chances of vertical transmission of Hepatitis B are 90%. This high transmission rate occurs when the mother has a high viral load, particularly if she is positive for the Hepatitis B e-antigen (HBeAg). In such cases, the risk of transmission to the newborn can be as high as 90% if no preventive measures are taken. The mechanism involves the baby coming into contact with infected maternal blood and vaginal secretions during delivery.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option suggests a much lower risk than what is observed in clinical practice for vertical transmission of Hepatitis B.
* **Option B:** This option also underestimates the risk of vertical transmission.
* **Option D:** This option overestimates the risk, though 90% is a commonly cited figure for mothers with high viral loads.

## **Clinical Pearl / High-Yield Fact**
A crucial preventive measure against vertical transmission of Hepatitis B is administering Hepatitis B immune globulin (HBIG) and the first dose of Hepatitis B vaccine to the newborn within 12 hours of life. This strategy significantly reduces the risk of transmission and is recommended for all newborns of Hepatitis B-positive mothers.

## **Correct Answer:** . 90%