Aortic function during normal human pregnancy.

Arterial rupture and dissection have been observed in both normal and complicated pregnancies. To understand how arterial mechanical properties might change during pregnancy, we measured aortic root diameter by M-mode echocardiography and obtained simultaneous cuff blood pressures during systole and diastole at rest and during isometric exercise. Measurements were obtained in 19 women at the end of normal gestation and again 3 to 6 months post partum. The aorta is larger and more compliant during normal human pregnancy, and these changes may not revert to prepregnant levels post partum. Increased aortic compliance, combined with decreased vascular resistance, may enhance left ventricular performance in normal pregnancy. Conversely, the presumed structural alterations leading to increased compliance may weaken diseased vessels leading to dissection or rupture during pregnancy.