Abstract: The monitoring of umbilical artery blood flow，a noninvasive，simple and convenient method，is widely used in clinic in order to evaluate fetal health and predict the perinatal outcomes. It is a sensitive method to monitor fetal distress in those high-risk pregnancies. The common causes of abnormal umbilical artery blood flow include placental dysfunction，abnormal umbilical cord，fetal abnormalities，gestational hypertension disease，fetal growth retardation（FGR） and so on. Abnormal umbilical artery flow，such as absent flow and the reversed end-diastolic velocity during pregnancy，is associated with intraventricular hemolysis，periventricular leukomalacia, neurodevelopmental impairment，bronchopulmonary dysplasia, respiratory distress syndrome，necrotic enteritis，thrombocytopenia，and even perinatal mortality. Pregnant women with complications，such as preeclampsia and FGR，should be advised to evaluate the umbilical artery doppler velocimetry. It was suggested that delivery should be considered in those pregnant women whose FGR and absent end-diastolic umbilical artery flow were found at ＞34 weeks，and that fetal lung maturity should be antenatally induced by corticosteroids for premature delivery if absent or reversed end-diastolic flow was found at ＜34 weeks.

Key words: Umbilical arteries, Fetal growth retardation, Pregnancy outcome