To identify the relationship between a systolic or diastolic notch in uterine artery flow velocity waveforms and pregnancy outcome, we studied 140 hypertensive pregnant women with transvaginal, image-directed pulsed Doppler ultrasound. The subjects were classified according to the presence or absence of a systolic or diastolic notch. In 14 with a systolic and 25 with a diastolic notch, the resistance indexes in the uterine arteries on both sides of the uterus were significantly higher than in 101 subjects without a notch. Those with notches had significantly higher rates of fetal growth retardation and cesarean delivery because of fetal distress. Significantly more infants born to women with a notch spent longer than 48 hours in the neonatal intensive care unit. Subjects with a systolic notch also had significantly higher rates of abnormal fetal heart rate patterns during labor and low Apgar scores at 5 minutes. Fifty-one women with elevated resistances indexes in both uterine arteries were divided into two groups according to the resistance index in the umbilical artery. Each group was subdivided according to the presence or absence of a systolic or diastolic notch in the uterine artery flow velocity waveforms. In the group with a normal resistance index in the umbilical artery, five women had growth-retarded fetuses when a notch was present (N = 8), compared with none in women without a notch (N = 11) (P less than .005). The respective figures for the group with abnormal umbilical artery resistance indexes were 14 of 19 (73.7%) and two of 13 (15.4%) (P less than .002).(ABSTRACT TRUNCATED AT 250 WORDS)