Abstract： Objective To explore the relation between single umbilical artery with other malformations and pregnancy outcome,and to provide evidence for pregnancy counseling and diagnosis.Methods The outcomes of 92 fetuses with single umbilical artery diagnosed and delivered in Beijing Obstetrics and Gynecology Hospital Affiliated to Capital Medical University from September 2007 to July 2009 were followed up and retrospectively analyzed with Chi-square test.Results Among 25 292 pregnant women,92 cases were finally diagnosed as single umbilical artery giving the incidence of 0.36％,among which 57.6％ (53/92) of newborns survived without malformations,15.2％(14/92) survived with malformations and 27.2％ (25/92) died during perinatal period.There were 36 fetuses (39.1％,36/92) with single umbilical artery complicated with other malformations,among which 29 had single malformation (80.6 ％ ),and seven ( 19.4 ％ ) had multiple malformations.The incidence of heart defects was the highest among the complicated malformations,and then followed by central nervous system,digestive system,motor system and urinary system.Thirty-three fetuses with single umbilical artery accepted karyotype analysis.Chromosome abnormality was diagnosed in three subjects (9.1％,3/33).Twenty-three fetus (25.0％,23/92) associated with small for gestational age,and among which 18 fetuses (78.3％,18/23) died with a higher mortality than that (4.0％,24/597) of small for gestational age patients without single umbilical artery (x2=181.71,P＜0.01).Conclusions Single umbilical artery is likely to be complicated with congenital anomalies.After single umbilical artery was diagnosed by routine ultrasound,fetal ultrasonography,echocardiography and amniocentesis for karyotype analysis is suggested.Fetal growth restriction is an important indicator of fetal adverse outcomes.