Background: Threatened abortion is presumed when there is a bloody vaginal discharge or bleeding through a closed cervical os. cancer antigen 125 (CA-125), B-Human chorionic gonadotropin (B-hCG), and Soluble vascular endothelial growth factor receptor (sVEGFR-1 or sFlt-1R) are biochemical markers that have been studied to establish if they can predict the outcome of threatened miscarriage. Methods: A prospective observational study that was conducted at the Department of Obstetrics and Gynecology at Azadi Teaching Hospital/ Kirkuk-Iraq, over a period of eight months from first of April 2019 till first of December 2019. It included 96 pregnant women at 7 – 13 weeks of gestation with singleton pregnancy, viable fetus, and closed cervical os they presented with signs and symptoms of first trimester threatened miscarriage. After the first visit, follow up was done until they passed into the second trimester of pregnancy, and patients from the study group were divided into group 1: Included 19 patients who ended with miscarriage and group 2: Included 69 women who continued their pregnancy into the second trimester. We compared the level of the Cancer antigen 125 (CA-125), B-Human chorionic gonadotropin (B-hCG), and Soluble vascular endothelial growth factor receptor (sVEGFR-1 or sFlt-1R) between the two study groups to assess their utility for prediction of the outcome of first-trimester threatened miscarriage. Results: Mean of CA 125 marker was significantly higher in participants who ended with miscarriage than that in participants who continued to second trimester. Means of B-hCG and sFlt-1markers were significantly lower in participants who ended with miscarriage than that in participants who continued to second trimester Serum CA-125 marker > 38.8 IU/ml, Serum β-hCG marker < 20211.3 mIU/ml, and serum sFlt-1 marker < 1731.7 pg/ml are predictors for risk of miscarriage. Conclusion: Serum CA 125, B-hCG, and sFlt-1 biomarkers represent non-invasive, early, fast and excellent predictors of pregnancy outcome in women with threatened miscarriage. Taking into account the feasibility and cost, using serum β-hCG instead of the more accurate one (i.e. serum sFlt-1) would be more logical decision. Further studies are needed in this field.