Blood flow velocity waveforms at late pregnancy and during labor.

608 high-risk pregnancies were monitored by repeated Doppler-examinations of the fetal aortic blood flow. An absent end-diastolic flow pattern was found to reveal fetal growth retardation with 73% sensitivity. The positive predictive value of this finding for prediction of fetal growth retardation combined with intrauterine distress (prevalence in the material 8%) was 85%. In the cases with this flow pattern, the cesarean section rate was 72%, and the mean gestational age at delivery was 34 weeks. Normal labor was not associated with any changes of umbilical arterial flow velocity waveforms, but the diastolic flow of the arcuate arteries was decreased during uterine contractions.