Increased plasma concentrations of antiprothrombin antibodies in women with recurrent spontaneous abortions

BACKGROUND: Antiphospholipid antibodies are associated with recurrent fetal loss, but the clinical relevance of antiprothrombin (aPT) antibodies remains controversial. This study was designed to evaluate the relationship of plasma concentrations of aPT antibodies (IgG, IgM, and IgA isotypes) and recurrent spontaneous abortion (RSA) not associated with antiphospholipid-antibody syndrome. METHODS: In this retrospective case-control study, we measured plasma aPT antibodies in 100 pregnant women at 8-12 weeks of gestation who had histories of recurrent abortion not associated with antiphospholipid-antibody syndrome. The controls were 200 healthy gestational-age-matched women with uncomplicated gestations. RESULTS: The mean (SD) plasma aPT concentrations were significantly (P <0.001) higher in women with histories of recurrent abortion than in healthy controls [7.97 (0.79) and 2.08 (0.07) kU/L]. Similarly, the concentrations of IgM aPT were significantly (P <0.001) higher in patients than in controls [5.73 (0.85) and 1.83 (0.05) kU/L]. No differences were found for IgA aPT (P = 0.358). CONCLUSIONS: High concentrations of aPT antibodies (IgG and IgM isotypes) are associated with pregnancy loss in women with RSA. We suggest that the antibodies may have a relevant role in the etiology and pathogenesis of the condition.