Background: First trimester recurrent pregnancy loss is three or more consecutive miscarriage which can be due to genetic, anatomical, endocrinological, immunological, microbiological and environmental factors. Objective: To evaluate the correlation between each of the ultrasound parameters that  assessed in the first trimester(the gestational sac size, yolk sac size, crown rump length  and fetal cardiac activity ) to early pregnancy loss. Patients and Methods: This was a prospective study of 100 (1 hundred) pregnant women in their first trimester that were carried out in the outpatient clinic and Emergency Department – Obstetrics and Gynecology Department – Al-Sayed Galal Hospital and Basyoun  Hospital during the period from 1st April 2020 till 1st October 2020.They classified into two equal groups: Group I: Pregnant women with history of first trimester recurrent pregnancy loss as cases. Group II: Pregnant women with history of normal obstetric history as controls. Transvaginal ultrasound scan was used to assess mean gestational sac diameter, yolk sac, crown-rump length and fetal heart rate. Results: The gestational sac diameter grew 6.65 mm per week in ongoing pregnancy group, and it was smaller in the pregnancy loss group. However, the difference was not significant until 8 weeks of pregnancy when the median diameter of the gestational sac was 15 mm in pregnancy losses, and 31 mm in ongoing pregnancy (p < 0.001). The yolk sac grew 0.38 mm per week in ongoing pregnancy group with p wave <0.001 at 10th week.      In pregnancy loss group, the yolk sac was either smaller or larger than in ongoing pregnancy group. The crown-rump length grew 7.54 mm per week, and was significantly larger in the ongoing pregnancy than in the pregnancy loss group from 6^th -10^th week with p value <0.001. The embryonic heart rate less than 100 b/m was associated with higher risk of pregnancy loss. Conclusion: The diagnosis of miscarriage was made in the presence of fetal pole 10 mm with no fetal heart activity, or the gestational sac diameter was 25 mm but no fetal pole could be demonstrated. In cases of an empty gestational sac 25 mm in diameter, a repeated scan was carried out 1-2 weeks later.