Uteroplacental circulation, preeclampsia, and maternal abdominal aortic stiffness in normal and compromised pregnancies.

A study of 82 normal and 60 compromised pregnant women who were identified by uterine artery Doppler flow waveform systolic/diastolic ratio >95th percentile (increased peripheral resistance) was carried out to examine the elastic properties of the maternal abdominal aorta (AA). An aortic stiffness index (SI) was measured between 18 and 40 weeks at four-weekly intervals with a phase-locked loop ultrasound technique to estimate the aortic systolic and diastolic diameters and their correlation with blood pressure. In the normal group, the aortic systolic and diastolic diameters, as well as the SI, increased with the maternal age. In the compromised group, aortic diameter and blood pressure were normal, but the SI during the early second trimester was increased. Twenty-two women from the compromised group with an SI above the 95th percentile for their age had a significantly higher prevalence of preeclampsia in comparison with women with a normal SI (P<0.001). The aortic SI was significantly higher in severe than in mild preeclampsia. This study demonstrates that stiffness of the AA is increased in pregnant women with preeclampsia and that a progressive increase of the SI in serial studies is associated with severity of the disease. Aberrant hemodynamic adaptation in preeclampsia seems to include increased stiffness of the larger artery besides high resistance in small peripheral arteries.