**Core Concept**
Intrahepatic cholestasis of pregnancy (IHCP) is a condition characterized by pruritus and elevated liver enzymes, occurring in the second or third trimester of pregnancy. The underlying pathophysiology involves impaired bile salt transport, leading to an accumulation of bile acids in the bloodstream, which causes pruritus and liver enzyme elevation.

**Why the Correct Answer is Right**
The management of IHCP involves the administration of ursodeoxycholic acid (UDCA), a bile acid that helps to reduce the accumulation of bile acids in the bloodstream. UDCA works by increasing the expression of the bile salt export pump (BSEP) and the multidrug resistance-associated protein 2 (MRP2), which are responsible for the transport of bile acids out of the hepatocytes. This leads to a decrease in the levels of bile acids in the bloodstream, thereby alleviating the symptoms of pruritus and reducing the risk of complications such as preterm labor and fetal distress.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because corticosteroids are not the primary treatment for IHCP. While corticosteroids may be used to promote fetal lung maturity in cases of preterm labor, they do not address the underlying pathophysiology of IHCP.

**Option B:** This option is incorrect because vitamin K is not indicated in the management of IHCP. Vitamin K is used to prevent bleeding in newborns, particularly in cases of maternal anticoagulation or liver disease.

**Option C:** This option is incorrect because magnesium sulfate is used to prevent preterm labor and treat eclampsia, not IHCP.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that IHCP is a risk factor for preterm labor and fetal distress, and therefore, close monitoring of fetal well-being is essential in the management of this condition.

**Correct Answer:** B. Ursodeoxycholic acid (UDCA)