Uterine artery flow velocity waveforms in normal and growth-retarded pregnancies

Uterine artery flow velocity waveforms were measured by continuous-wave Doppler ultrasound in 15 normal pregnant women studied from midgestation until term. Results were analyzed by calculation of the pulsatility index and the systolic/diastolic blood pressure ratio. Both indices decreased from 16 to 20 weeks (indicating a lowering of resistance) and thereafter remained stable until term. Resistance was lower when waveforms were recorded...