ABSTRACT
In the later stages of pregnancy, the weight of the fetus and the uterus may dramatically influence cardiovascular performance. In the supine position, they may compress the inferior vena cava and reduce systemic venous return and, therefore, cardiac output. The left lateral decubitus position minimizes compression of the inferior vena cava. During labor and delivery, cardiac output increases further in the context of pain, anxiety, and physical exertion. Uterine contractions are often accompanied by increases in diastolic and systolic blood pressure. Following delivery, a surge in preload is produced by the redistribution of uterine blood into the systemic circulation and by the relief of partial caval obstruction.
