Hypothesis/aims of study. Patients with a history of pregnancy complications that meet the clinical criteria of antiphospholipid syndrome (APS), with circulation of autoantibodies not related to the laboratory criteria for APS, present difficulties in choosing a method for preventing recurrent complications. The aim of this study was to determine the frequency of autoantibodies in women with severe obstetric complications and habitual miscarriage and to evaluate the effectiveness of therapy used in APS for the prevention of recurrent reproductive losses in women with non-criteria autoantibodies.
 Study design, materials and methods. 358 women with a history of APS clinical criteria or two pregnancy losses up to 10 weeks were examined. Anti-beta2-glycoprotein I and anti-cardiolipin (IgG/IgM) antibodies, as well as non-conventional autoantibodies for phosphatidylinositol, phosphatidylserine, phosphatidyl acid, annexin V, and prothrombin were determined in serum, with lupus anticoagulant test performed. In 39 women with clinical criteria for APS and circulating anti-annexin V or prothrombin antibodies during pregnancy, enoxaparin sodium was used (in 100% of the cases) in combination with acetylsalicylic acid (ASA) at a dose of 50-100 mg per day (in 69.2% of the cases).
 Results. The frequency of all types of autoantibodies was 38.8%. Non-conventional antibodies were detected in 17.6% of the cases (isolated circulation in 11.5% of the cases); with anti-annexin V antibodies (73.0%) prevailed among them. In 39 patients with non-criteria antibodies, after the use of a prophylactic dose of enoxaparin sodium and ASA, live births were the outcome of pregnancy in 84.6% of the cases.
 Conclusion. Testing for non-conventional autoantibodies may be appropriate in patients with only APS clinical criteria. Standard treatment of APS prescribed for this group of patients led to a significant increase in the frequency of live births. Further large studies are needed to evaluate the efficacy of medical prophylaxis of adverse pregnancy outcomes in women with non-criteria obstetric ABS.