ORIGINAL ARTICLES 681 21 2019 Background: Recurrent miscarriages are associated with a high prevalence of thrombophilia. Use of a calibrated automated thrombogram (CAT) can serve as a universal test for thrombophilia. Objectives: To examine whether thrombin generation measur- ed by CAT is elevated during the first trimester in women with unexplained recurrent miscarriages. Methods: This study comprised 25 pregnant women with recurrent pregnancy loss referred for thrombophilia screening and treated with low-molecular-weight heparin (LMWH). Thrombin generation parameters were measured in women who had miscarriages or live births and who were diagnosed as positive or negative for thrombophilia. Results: Of the pregnancies, 76% resulted in live birth and 24% ended in miscarriages. Among the women, 76% were positive for thrombophilia. Thrombin generation parameters between pregnancies that ended in miscarriage compared to live births were not significantly different, and CAT parameters failed to predict pregnancy outcome. Although the CAT parameters demonstrated a trend toward a hypercoagulable state in women with thrombophilia, there was no statistical significance (P > 0.05). Conclusions: Women with unexplained pregnancy loss demonstrated similar thrombin generation in the first trimester, regardless of the pregnancy outcome. CAT parameters failed to predict pregnancy outcome in women with recurrent unexplained pregnancy loss. Our results should be interpreted with caution due to the small number of participants. IMAJ 2019; 21: 681–685 anti-thrombotic treatment, calibrated automated thrombogram (CAT), thrombin generation, thrombophilia, recurrent miscarriages Calibrated Automated Thrombogram During Pregnancy in Unexplained Recurrent Miscarriages: A Pilot Study Adi Elias MD 1 , Rudi Hamoudi MD 4 , Naama Schwartz PHD 3 , Gilat Ron MPH 2 and Mazen Elias MD 2,4 1 Department of Internal Medicine B, Rambam Medical Center, Haifa, Israel Departments of 2 Internal Medicine C and 3 Statistics and Epidemiology, Emek Medical Center, Afula, Israel 4 Rappaport Faculty of Medicine, Technion–Israel Institute of Technology, Haifa, Israel ABSTRACT: KEY WORDS: T he incidence of miscarriages in healthy women is about 15% of all pregnancies. Te prevalence of recurrent mis- carriages is approximately 1–2% [1]. Te etiology for recur- rent miscarriages can be embryonic, anatomic, chromosomal, or maternal disorders that create a hostile environment for the fetus. Tis happens in the case of endocrinological disor- ders and congenital or acquired thrombophilia. Chromosome analysis could explain 80% of unexplained recurrent miscar- riages in women more than 35 years old [2,3]. Nevertheless, a large number of miscarriages remain unexplained despite comprehensive investigation. Te term recurrent miscar- riages is defned as three early or two late miscarriages and has a prevalence of 1–2% in women of reproductive age [4]. Recurrent miscarriages are a predictable complication in conditions of hypercoagulation. Multiple studies have indicated a connection between recurrent miscarriages and acquired or congenital thrombophilia [5]. Mutations in factor V Leiden, protein S defciency, protein C defciency, or antithrombin III defciency could increase the incidence of unexplained recur- rent miscarriages. Factor V Leiden was associated with early and late recurrent miscarriages as were prothrombin muta- tion and protein S defciency [6]. Moreover, the prevalence of thrombophilia in unexplained pregnancy loss was 78% [7], and there is a demonstrated link between thrombophilia and obstetric complications such as preeclampsia, placental abrup- tion, fetal growth retardation, or stillbirth [8]. Anticoagulant treatment with low-molecular-weight hepa- rin (LMWH) at a dosage of 40 mg once daily or other antico- agulants for women with recurrent miscarriages and thrombo- philia leads to improved obstetric outcomes [9,10]. However, these fndings do not prove the efcacy of heparin treatment due to a lack of control groups in the aforementioned studies [11].Conversely, the chance for live births without treatment in these women is over 50%, thus the efcacy of anticoagulant treatment in recurrent miscarriages was inconclusive. Tus, additional randomized controlled trials (RCTs) are needed [12]. In the past, the common approach was to perform throm- bophilia testing for every woman with a medical history of recurrent miscarriages or one miscarriage afer gestational week 10. Te cause of thrombophilia was determined in 50% of the patients. In the event of positive tests for thrombophilia, anticoagulation treatment during pregnancy was suggested. Even in the case of negative tests, anticoagulant treatment was proposed in chosen cases. Current guidelines recommend that only antiphospholipid syndrome workup be performed, with- out further thrombophilia diagnosis [13,14]. According to a