OBJECTIVE: To evaluate the prognostic value of umbilical artery Doppler studies in premature deliveries. METHODS: In this cohort study of 582 singleton pregnancies delivered between 24 and 35 weeks of gestation, we evaluated the ratio of peak-systolic to end-diastolic (S/D) blood flow velocities in the umbilical artery of all the patients. The correlations among the results of the Doppler studies, short-term neonatal complications, and the infantsneurodevelopmental outcome at 2 years were studied by univariable and multivariable methods. RESULTS: The prevalences of either neonatal death or cerebral palsy among the 266 (45.7%) growth restricted fetuses were 3.4%(3/88) in pregnancies with a S/D ratio below the 95th percentile, 4.9%(5/103) in pregnancies with a S/D at or above the 95th percentile, and 17.3%(13/75) in those with absent or reversed end-diastolic blood flow in the umbilical artery (P for trend = .001). The corresponding figures in the 316 pregnancies with adequate fetal growth were 6.4%(15/234) and 4.3%(3/69) among pregnancies with a S/D ratio below and at or above 95th percentile, respectively, whereas no cases of either neonatal death or cerebral palsy were recorded in the 13 pregnancies with adequate fetal growth and absent or reversed end-diastolic blood flow velocity (P for trend = .28; χ2 for heterogeneity of linear trends compared with growth-restricted infants = 7.02, P = .008). In logistic regression, in pregnancies complicated by fetal growth restriction, absent or reversed enddiastolic blood flow in the umbilical artery was still associated with an increased risk of either neonatal death or cerebral palsy even after adjustment for gestational age and proportion of expected birth weight, (odds ratio 3.2, 95%confidence interval 1.18-8.66, P = .02). CONCLUSION: Absent or reversed enddiastolic flow in the umbilical artery is an independent predictor of either neonatal death or cerebral palsy in preterm growthrestricted fetuses. In the absence of fetal growth restriction, umbilical artery Doppler study was associated with none of the infant outcome parameters studied. OBJECTIVE: To evaluate the prognostic value of umbilical artery Doppler studies in premature deliveries. METHODS: In this cohort study of 582 singleton pregnancies delivered between 24 and 35 weeks of gestation, we evaluated the ratio of peak-systolic to end- diastolic (S / D) blood flow velocities in the umbilical artery of all the patients. The correlations among the results of the Doppler studies, short-term neonatal complications, and the infants  developmental outcome outcome at 2 years were studied by univariable and multivariable methods. RESULTS: The prevalences of either neonatal death or cerebral palsy among the 266 (45.7%) growth restricted fetuses were 3.4% (3/88) in pregnancies with a S / D ratio below the 95th percentile, 4.9% (5/103) in pregnancies with a S / D at or above the 95th percentile, and 17.3% (13/75) in those with absent or reversed end-diastolic blood flow in the umbilical artery (P for trend = .001). The corresponding figures in the 316 pregnancies with adequate fetal g rowth were 6.4% (15/234) and 4.3% (3/69) among pregnancies with a S / D ratio below and at or above 95th percentile, respectively, with no cases of either neonatal death or cerebral palsy were recorded in the 13 pregnancies with adequate fetal growth and absent or reversed end-diastolic blood flow velocity (P for trend = .28; χ2 for heterogeneity of linear progression compared with growth-restricted infants = 7.02, P = .008). In logistic regression, in pregnancies complicated by fetal growth restriction, absent or unexplained with an increased risk of either neonatal death or cerebral palsy even after adjustment for gestational age and proportion of expected birth weight, (odds ratio 3.2, 95% confidence interval 1.18-8.66, P = .02). CONCLUSION: Absent or reversed end of diastolic flow in the umbilical artery is an independent predictor of either neonatal death or cerebral palsy in preterm growthrestricted fetuses. In the absence o f ffetal growth restriction, umbilical artery Doppler study was associated with none of the infant outcome parameters studied.