A pulsed Doppler screening study was performed on pregnant women to investigate the ability of the test to detect adverse pregnancy outcome by following two methods. The waveforms were analyzed by calculating the resistance index (RI). Method 1.: longitudinal study: Blood flow velocity in the umbilical artery (UA) was recorded at 23, 28, 32, and 35 weeks' gestation in 726 pregnancies. Method 2.: cross-sectional study with FAS: Blood flow velocity in the UA and fetal middle cerebral artery (MCA) was recorded before and after fetal acoustic stimulation (FAS) at 35 weeks' gestation in 525 pregnancies. Result 1.: As UA-RI decreases continuously with gestational age, there was a linear correlation between them. The 726 cases were classified into three groups according to the UA-RI value. The UA-RI of the control group (n = 698) never reached mean + 2SD. The UA-RI of the +2.5D group (n = 4) increased with gestational age and was over mean +2.5SD at the last measurement. The +2SD group (n = 24) remained. There was a significant adverse pregnancy outcome in the +2.5SD group as judged by intrauterine growth retardation (SGA) (+2.5SD; 75%, +2SD; 17%, control; 10%), fetal distress (+2.5SD; 75%, +2SD; 5%; control; 9%) and pregnancy induced hypertension (+2.5SD; 75%, +2SD; 23%, control; 8%). Result 2.: The normal ranges of UA-RI and MCA-RI were calculated at 35 weeks' gestation, both before and after FAS, and women with UA-RI > +2SD or MCA-RI < -2SD were considered as abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)