## **Core Concept**
Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality worldwide. It is defined as excessive bleeding following delivery, typically exceeding 500 mL after vaginal delivery or 1000 mL after cesarean section. Various risk factors contribute to the likelihood of developing PPH.
## **Why the Correct Answer is Right**
The correct answer, ., is associated with a lower risk or is not a risk factor for PPH. In the context of PPH risk factors, previous uterine surgery, multiple gestations, and overdistended uterus are known to increase the risk. A history of a previous cesarean section may not necessarily increase the risk of PPH, especially if there were no complications.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Previous uterine surgery can lead to complications such as placenta accreta, increta, or percreta, which significantly increase the risk of PPH.
- **Option B:** Multiple gestations can lead to uterine overdistension, which is a known risk factor for PPH due to the potential for uterine atony.
- **Option C:** Overdistended uterus, often due to conditions like polyhydramnios or multiple gestations, increases the risk of PPH primarily because it can lead to uterine atony.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that uterine atony is the most common cause of PPH, and risk factors for uterine atony include uterine overdistension (as seen in multiple gestations or polyhydramnios), prolonged labor, and previous history of uterine surgery or PPH.