Which statement about cardiovascular changes around birth is correct?

Which statement about cardiovascular changes around birth is correct?

• A. Blood pressure systolic increases substantially
• B. Systemic vascular resistance remains elevated after mid-pregnancy
• C. Cardiac output is higher immediately after birth than prepregnancy
• D. Minute ventilation decreases with term

Answer: (C)

After birth, the uterus contracts and the placental circulation ends, causing autotransfusion of blood back into the maternal circulation. This increases preload (venous return) to the heart and, along with the sudden drop in placental vascular resistance, leads to a transient rise in cardiac output right after delivery. That’s why the statement that cardiac output is higher immediately after birth than prepregnancy is the best answer. Cardiac output often stays above prepregnant levels for hours to days postpartum and then gradually returns toward baseline. Other postpartum changes don’t fit as well: systemic vascular resistance does not stay elevated after mid-pregnancy; it falls during pregnancy and normalizes after birth as placental circulation ends. Blood pressure isn’t known to rise substantially in the immediate postpartum period. Minute ventilation actually increases during pregnancy due to hormonal influences and metabolic needs and remains elevated for a time after birth, rather than decreasing.

After birth, the uterus contracts and the placental circulation ends, causing autotransfusion of blood back into the maternal circulation. This increases preload (venous return) to the heart and, along with the sudden drop in placental vascular resistance, leads to a transient rise in cardiac output right after delivery. That’s why the statement that cardiac output is higher immediately after birth than prepregnancy is the best answer. Cardiac output often stays above prepregnant levels for hours to days postpartum and then gradually returns toward baseline.

Other postpartum changes don’t fit as well: systemic vascular resistance does not stay elevated after mid-pregnancy; it falls during pregnancy and normalizes after birth as placental circulation ends. Blood pressure isn’t known to rise substantially in the immediate postpartum period. Minute ventilation actually increases during pregnancy due to hormonal influences and metabolic needs and remains elevated for a time after birth, rather than decreasing.