Introduction: The presence of antiphospholipid (aPL) antibodies increases the risk for recurrent miscarriage (RM). Annexins are a family of structurally related proteins which all bind to anionic phospholipids (PLs) preventing clotting on vascular phospholipid surfaces. The aim of our study was to define plasma concentrations of circulating annexins IV and V at the beginning of pregnancy among women with a history of RM, and in connection to their aPL antibody status. Materials and methods: Sixty-eight women with RM and 25 controls without history of adverse pregnancy outcome were included in the study. Concentrations of annexins IV and V in plasma were determined by using a sandwich ELISA technique. Results: Hereditary or acquired thrombophilic disorders were found in 53% (36/68) of the patients with RM. Plasma levels of annexin V were significantly higher at the beginning of pregnancy (P = 0.03), at the 6th (P = 0.01) and 8th week of pregnancy in women with aPL antibodies compared with those without aPL antibodies. A tendency towards higher plasma levels of annexin V was observed in those whose pregnancies ended in miscarriage compared with those with successful pregnancy, although the results did not reach statistical significance (P = 0.10). Plasma levels of annexin IV at the first visit in women with aPL antibodies were similar to those at 6 and 8 weeks of gestation. There were no significant differences in plasma annexin IV levels between women with and without aPL antibodies. Conclusions: Patients with RM show elevated plasma levels of annexin V in presence of aPL antibodies. These antibodies could displace annexin from anionic phospholipid surfaces of syncytiotrophoblasts (STBs) and hereby promote coagulation activation.
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