Recurrent pregnancy loss: Etiology of thrombophilia

Congenital and acquired thrombophilia are associated with an increased risk of pregnancy-associated venous thrombosis and fetal loss. Two hundred eigh ty-nine patients with a history of recurrent spontaneous abortion were subj ected to screening examinations for the etiology of these abortions. Endocr ine abnormality (28.0%), uterine abnormality (10.4%), autoimmune diseases ( 1.4%), antiphospholipid antibody syndrome (4.5%), and balanced type chromos ome translocation (4.2%) were found as underlying causes of recurrent abort ions, and the remaining 55.0% of the 289 patients were classified as having an unexplained etiology. Congenital thrombophilia such as protein C (PC) d eficiency, protein S (PS) deficiency, antithrombin deficiency, and factor V Leiden mutation was not frequently detected; only one patient had PS defic iency. A reduced factor XII activity was found at a frequency of 4.2%. The frequency of methylene tetrahydrofolate reductase gene C677T mutation in re current aborters (0.38) was the same as that found in a fertile control gro up. Although the prevalence of anti-beta2-glycoprotein I antibody (a beta2- GPI) syndrome was very low (1.7%), patients with a high titer of immunoglob ulin G (IgG) class a beta2-GPI, despite anticoagulation therapy, experience d severe fetomaternal complications in subsequent pregnancies. The rate (13 .8%) of positive tests for serum IgA class a beta2-GPI in patients with une xplained etiology was higher than that in the controls (0%) (P < .05). We c onclude that congenital thrombophilia is rare in Japanese patients who had experienced consecutive spontaneous abortions.