Background: it is estimated that approximately 30% to 40% of implanted pregnancies resulted in spontaneous abortion during the first trimester, most of which occur in very early stage. Significant number of losses predominantly occurs very early in gestation, but once the embryonic heart activity appears the rate of spontaneous abortion gradually decreases to 2-5%. Aim of the work: this work aimed to evaluate the correlation between the ultrasound parameters that were assessed in the first trimester (the gestational sac size, yolk sac size and shape and embryonic heart rate) to early pregnancy loss and the correlation between different ultrasound parameter to each other. Methodology: this study involved 100 pregnant women attending Al Hussein University Hospital. They were examined by using 2D ultrasonography starting early in the first trimester with a first scan between 6 and 8 weeks. A follow up scan was conducted at 9 and 12 weeks. During follow up, 7 women did not return for follow up and accordingly, the results (gestional sac diameter,embryonic heart rate and yolk sac size and shape ) of the remaining 93 women were shown. All patients were evaluated by transvaginal ultrasound using equipped with a real-time, 5-MHz sector electronic array endovaginal probe. The fetal heart rate was measured by M-mode in all cases and the yolk sac diameter (YSD) was determined by placing the calipers on the inner limits of the longer diameter. Results: in this study, there was a significant increase in age in fetal loss group more than complete pregnancy group. Regarding the relation between gestational sac diameter at different gestational age period and its relation to the outcome of pregnancy, the gestational sac diameter showed a significant decreasing in the fetal loss group at 6, 9 and 12 weeks, so the GS diameter was a good predictor to fetal loss (p < 0.05). Conclusion: first trimester ultrasound measurement of these parameters (FHR,YS diameter and shape and GS diameter) proved to be an important, helpful and noninvasive tool in the investigation, diagnosis as well as the follow up of pregnant females in their early pregnancy. Measurement of gestational sac diameter, CRL and fetal heart rate in combination provided better prediction of the prognosis of the first trimester than when either parameter used alone.