To evaluate the clinical utility of third trimester Doppler waveform analysis of the uterine artery in predicting complicated pregnancies and fetal well-being, we compared adverse pregnancy outcomes in 2321 women with the presence of an elevated systolic-diastolic ratio (greater than 2.6) with the persistence of an early diastolic notch and with the combination of an elevated systolic-diastolic ratio and an early diastolic notch. The positive predictive values are 47.5%, 82.9%, and 92.6%, respectively. From these data we can conclude that determination of the presence or absence of an early diastolic notch is more valuable in predicting the perinatal outcome than is the presence of an elevated systolic-diastolic ratio alone. We also suggest that an assessment of the uterine artery systolic-diastolic ratio combined with the evaluation for persistent early diastolic notch would be a clinically useful test for fetal well-being.