What physiologic postpartum change occurs because the uterus shrinks in size, resulting in an increase in blood flow?
Correct Answer: B
Rationale: The correct answer is B: Cardiac output increases. As the uterus shrinks in size postpartum, it stimulates an increase in blood flow to the area, leading to an increase in cardiac output to meet the demands. This is a normal physiologic response that helps to prevent excessive bleeding and promote healing. Edema increasing (A) is not directly related to the shrinking uterus. Temperature rising (C) is not a typical postpartum change due to uterine involution. Lochia increasing (D) is not a direct result of uterine shrinkage, but rather a normal discharge after childbirth.