Development of uterine artery compliance in pregnancy as detected by Doppler ultrasound.

Uterine artery velocimetry was performed by means of a continuous-wave Doppler ultrasound. Serial studies were done on 12 nonpregnant and 79 normal pregnant women. Measurements were made on both uterine arteries and averaged. From the proliferative phase of the menstrual cycle through 40 weeks of pregnancy, four developmental phases are described. These changes are based on the calculation of the systolic-diastolic ratio and the disappearance of the early diastolic notch in the velocity wave. The ratio after 26 weeks averaged 2 +/- 0.3. These data provide a foundation for the study of pregnancies in which these normal evolutionary changes do not occur.