## Core Concept
Amniotic fluid embolism (AFE) is a rare but serious condition that occurs when amniotic fluid or fetal material enters the maternal circulation, triggering a severe reaction. This condition is often associated with obstetric interventions or complications. The risk factors and triggers for AFE are crucial for understanding its clinical management.

## Why the Correct Answer is Right
The correct answer, **C. Placenta previa**, is associated with a higher risk of amniotic fluid embolism due to the potential for disruption of the placental site and the maternal-fetal interface. Conditions that disrupt the integrity of the uterus or the placental implantation site increase the risk of AFE. Placenta previa, characterized by the placenta partially or wholly covering the internal cervical os, poses a significant risk due to its association with bleeding and potential uterine manipulation.

## Why Each Wrong Option is Incorrect
* **Option A:** While uterine rupture is a severe obstetric complication, it is not as directly associated with AFE as conditions that directly involve the placenta or amniotic sac.
* **Option B:** Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys. While serious, it is not directly linked to AFE in the same way as conditions involving direct disruption of fetal-maternal interfaces.
* **Option D:** Postpartum hemorrhage is a condition that can arise from various causes, including uterine atony, lacerations, and retained placental tissue. While it is a significant obstetric emergency, it is not specifically identified as a primary risk factor for AFE compared to conditions directly affecting the placenta.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that amniotic fluid embolism often presents with sudden cardiovascular collapse, respiratory distress, and coagulopathy. It is essential to maintain a high index of suspicion in cases of sudden maternal deterioration during delivery or shortly postpartum, especially in the presence of conditions like placenta previa or during procedures that might disrupt the uterine or placental integrity.

## Correct Answer: C. Placenta previa.