Background: Within the gestational sac, the yolk sac is the first embryonic structure to be seen. The size, shape, and function of the yolk sacs, as well as the heart rates of the developing embryos, all play a role in the evaluation and prognosis of first-trimester pregnancy losses. Objective: The purpose of this study was to determine if yolk sac diameter (YSD) and embryonic heart rate (HER) could be used to predict pregnancy outcomes. Patients and Methods: 52 pregnant women at gestational age ranged between 6-12 weeks who were included in the study. Our prospective cohort study was carried out in Obstetrics and Gynecology Department at Fetomaternal Unit, Zagazig University Hospital and Fetomaternal & Ultrasound Units, Matrouh Maternity Hospital. Measurements of the embryo's crown-rump length as well as their heartbeat rate and the size and shape of the yolk sac were done. Results: Normal sac diameter was seen in the great majority of YSD patients in the study groups (80.8 percent). Only one case of normal diameter YSD ended in miscarriage after the first trimester in all patients with normal YSD. A 98.1% success rate in predicting miscarriage was achieved by YSD, which had 97.6% sensitivity and 100% specificity. First-trimester pregnancy outcomes were accurately predicted by EHR with a sensitivity of 97.5% and a specificity of 100%. Conclusion: Maternal risk variables including age, weight, or parity have no effect on the poor pregnancy outcome related with abnormal yolk sac diameter and embryonic bradycardia.