Background: Color Doppler ultrasonography enables the non-invasive study of physiologic and pathophysiologic changes in the uterine and ovarian circulation in pregnant and non-pregnant women. Aim of the work:To evaluate the potential value of color Doppler of the uterine artery, corpus luteum blood flow, and subchorionic blood vessels in abnormal first-trimester pregnancy. Patients and methods: The study included 200 pregnant women in the first trimester in the antenatal care clinic of the Department of Obstetrics and Gynecology AL Azhar University [Assiut], divided into two groups; control group [100 cases] with normal pregnancy and study group [100 cases] which was further subdivided into threatened abortion [60 cases], blighted ovum [20 cases] and vesicular mole [20 cases]. Results:The uterine artery resistance index [RI] of the study groups was lower than the control group. The decrease was highly significant in the uterine artery RI of both threatened abortion and blighted ovum groups and significant in the vesicular mole group. Uterine artery pulsatility index [PI] showed a significant decrease in the study group compared with the control cases. There was a highly significant negative correlation between gestational age and both RI and PI of the study group's uterine artery. There was a higher prevalence of abortion in a group of threatened abortion compared to the control group. Conclusion:The prevalence of pregnancy complications is increased in association with abnormal blood flow patterns of the early uteroplacental circulation. Doppler indices of the early gestation uteroplacental circulation have an important value in the threatened abortion follow up.