During which period of labor does the greatest cardiac stress occur?

The immediate postpartum period is characterized by significant physiological changes in the mother's body as it transitions from labor to recovery. During this time, the cardiovascular system experiences substantial stress due to several factors, including rapid changes in blood volume and hemodynamics after the delivery of the placenta. This period requires the heart to adapt quickly to the loss of placental circulation and the redistribution of blood volume as the uterus contracts and returns to a non-pregnant state.

While the late first stage of labor, especially during transition, and the second stage of labor also impose stress on the cardiovascular system due to increased cardiac output, changes in intra-abdominal pressure, and the exertion involved with pushing, the immediate postpartum period represents the peak of these cardiovascular challenges. This is when the recovery phase begins, and the mother's body needs to stabilize blood pressure and manage fluid shifts effectively. These factors contribute to why the greatest cardiac stress occurs during the immediate postpartum period.