Early pregnancy loss is the most common pregnancy complication in the first trimester where up to 15% of pregnancies end in a miscarriage. Pregnancy in itself is a hypercoagulable state and can increase the risk of a venous thromboembolism by up to 4-5 times. Scientists have long speculated the role of inherited and acquired thrombophilia in adverse pregnancy outcomes. Many studies have been made on the subject, with conflicting results. So far, only acquired thrombophilia has been shown to have an established role in the pathogenesis of adverse pregnancy outcome. My objective in this thesis was to review the current literature and try to shed light on the current views and guidelines concerning the matter.