Low-molecular-weight Heparin Versus Unfractionated Heparin in Pregnant Women With History of Recurrent Abortion Secondary to Antiphospholipid Syndrome. A Randomized Controlled Trial

Women with antiphospholipid syndrome (APS) have live birth rates as low as 10% in pregnancies without pharmacological treatment. Low dose aspirin (LDA) ,unfractionated heparin(UFH) , Low molecular weight heparin (LMWH) , prednisone, and intravenous immunoglobulin (IVIG) have been used either alone or in combination in order to improve the live birth rate in APS positive women with recurrent miscarriage. A Cochrane review of 13 randomized or quasi-randomized, controlled trials of various management options of pregnant women with a history of pregnancy loss and APL, revealed that combined UFH and aspirin was the treatment of choice which reduced pregnancy loss by 54% .

During the past decade , low molecular weight heparins were widely used in the prophylaxis and treatment of patients with venous or arterial thrombosis ,with an efficacy and safety superior or at least equivalent to that of UFH .Although recent studies reported the use of LMWH in the management of patients recurrent pregnancy loss secondary to antiphospholipid syndrome resulted in encouraging results . It is not clear whether the efficacy and safety of LMWH is equivalent to that of UFH .

Although LMWH is more expensive than UFH . LMWH has longer half life , greater bioavailability , more stable dose-response relationship than UFH and therefore can be administered once daily. Furthermore, LMWH requires less frequent monitoring than UFH and and has less adverse effect on bone mineral density and platelet count .These advantages make LMWH more attractive for the patients and physicians than UFH .

There are only two studies which compared the efficacy of LMWH plus LDA with that of UFH plus LDA in the management of pregnant women with recurrent pregnancy loss secondary to APS. In addition ,no randomized controlled study has yet compared the efficacy of LMWH plus LDA with UFH plus LDA.

The aim of this study is to compare the efficacy and safety of Low molecular weight heparin (LMWH) plus low dose aspirin (LDA) with unfractionated heparin(UFH) plus LDA in women with recurrent pregnancy loss associated with antiphospholipid syndrome (APS).