Final answer:
Postpartum hemorrhage is defined as excessive bleeding after childbirth, typically with a blood loss greater than 500 mL.
Step-by-step explanation:
Postpartum hemorrhage refers to excessive bleeding that occurs after childbirth. The amount of blood loss that defines postpartum hemorrhage can vary, but typically it is considered to be a blood loss of greater than 500 mL. This blood loss may be measured directly or estimated based on clinical signs and symptoms. It is important to note that postpartum hemorrhage is a serious medical condition that requires prompt medical attention and intervention.