Objective:To investigate the changes of serum nitric oxide (NO) and endothelin-1 (ET-1) concentrations and their relationship with umbilical arteries blood flow velocities in gestational diabetes mellitus(GDM) women. Methods:A total of 45 pregnant women with GDM were collected as the GDM group,and 43 normal pregnant(NP) women were selected as the control group. They were awaiting delivery during January to October in 2012. All of them underwent antepartum glucose tolerance test in their prenatal examination. Ultrasonic testing of cord blood flow parameters(S/D) were measured for the GDM group and control group at one week before delivery. Venous blood samples were collected from all the subjects when they were awaiting delivery in hospital. Venous blood NO and ET-1 levels were detected by nitrate reductase and ELISA,respectively. Results:Compared with the control group,venous blood NO levels decreased and ET-1 levels and S/D increased significantly (P < 0.05) in the GDM group (P < 0.05). NO level was negative (r = -0.596,P < 0.05) and ET-1 level was positive (r = 0.610,P < 0.05) related with S/D value in the GDM group. The incidence of adverse pregnancy in the GDM group was higher than the control group. Conclusion:The decrease of NO and the increase of ET-1 content lead to the increase of blood flow resistance of the fetal-placental,which may be an important factor leading to adverse pregnancy in patients with GDM.