**Core Concept**
Hepatic encephalopathy in pregnancy, particularly in a woman with a history of previous pregnancy, is a serious condition that requires prompt identification of the underlying cause. The liver plays a crucial role in detoxification and metabolism, and its dysfunction can lead to encephalopathy, characterized by confusion, altered mental status, and eventually, coma.

**Why the Correct Answer is Right**
Hepatitis E is a waterborne viral hepatitis that disproportionately affects pregnant women, especially in developing countries. Infection with Hepatitis E virus (HEV) during pregnancy, particularly in the third trimester, can lead to severe liver dysfunction and subsequent hepatic encephalopathy. This is due to the virus's ability to infect and replicate within the liver cells, causing inflammation and damage. The pathophysiology of HEV infection in pregnancy is complex and involves the virus's interaction with the host's immune system, leading to an exaggerated inflammatory response and liver injury.

**Why Each Wrong Option is Incorrect**
**Option A:** Hepatitis B is a major public health concern, but it is not typically associated with hepatic encephalopathy in pregnancy. While Hepatitis B virus (HBV) can cause liver damage and cirrhosis, the risk of severe liver dysfunction and encephalopathy in pregnant women is relatively low compared to Hepatitis E.

**Option C:** Hepatitis D is a defective virus that requires co-infection with Hepatitis B to replicate. It can exacerbate liver damage in individuals with HBV infection but is not a primary cause of hepatic encephalopathy in pregnancy.

**Option D:** Hepatitis A is a self-limiting illness that typically resolves on its own without causing severe liver damage or encephalopathy. While Hepatitis A virus (HAV) can cause liver inflammation, it is not commonly associated with hepatic encephalopathy in pregnancy.

**Clinical Pearl / High-Yield Fact**
In pregnant women, Hepatitis E infection can lead to severe liver dysfunction and hepatic encephalopathy, highlighting the importance of prompt recognition and management of this condition. Clinicians should consider Hepatitis E in the differential diagnosis of hepatic encephalopathy in pregnant women, especially those with a history of previous pregnancy.

**✓ Correct Answer: B. Hepatitis E**