## **Core Concept**
Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality worldwide. It is defined as excessive bleeding following the birth of a baby, which can lead to shock, organ failure, and even death if not managed promptly and effectively. The definition of PPH is often quantifiable.

## **Why the Correct Answer is Right**
The correct answer, **1000 mL or 10% of total blood volume**, is based on the standard definition used in obstetrics. Postpartum hemorrhage is typically defined as blood loss exceeding 1000 mL or a 10% decrease in blood volume after delivery. This significant blood loss can occur within 24 hours of delivery and is a medical emergency.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 500 mL - While significant, blood loss of 500 mL is considered a normal blood loss during delivery. It does not meet the threshold for postpartum hemorrhage.
- **Option B:** 750 mL - This amount is below the standard threshold for defining postpartum hemorrhage.
- **Option D:** 1500 mL - Although this amount clearly indicates a postpartum hemorrhage, it is not the minimum threshold used for the definition.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the 10% decrease in blood volume criterion can vary depending on the patient's initial blood volume, which can change with pre-existing conditions like anemia. However, for practical purposes, 1000 mL is a universally accepted threshold.

## **Correct Answer:** C. 1000 mL.