Physiologic and Hemodynamic Changes During Pregnancy

Substantial physiologic changes accompany pregnancy, the most profound of which involve the cardiovascular system. These changes affect maternal hemodynamic and oxygen transport status. This article describes cardiovascular changes that occur during pregnancy including blood volume, heart rate, stroke volume, cardiac output, vascular resistance, and colloid osmotic pressure. Alterations in factors related to maternal oxygen transport including oxygen affinity, delivery, and consumption also are described. Concepts related to fetal oxygen transport and adaptive responses to hypoxemia are presented. Technical considerations regarding assessment of maternal hemodynamic and oxygen transport status during pregnancy are described and assessment findings during labor, birth, and the immediate postpartum period are interpreted. A maternal hemodynamic and oxygen transport profile is presented to illustrate these principles in clinical practice.