Effects of the pregnant uterus on the abdominal aorta and its branches.

The pregnant uterus was found to exert pressure upon the lumbar region with a maximum over the midline of the lordosis and diminishing laterally. Those parts of the arterial system formed by the aorta and its dorsal branches and displaceable at autopsy, were accordingly dislodged by the uterus, whereas the fixed parts were compressed. The pressure effects extended cranially during pregnancy. Symptoms of compression can be relieved by avoiding supine and prone positions.