Does low-molecular-weight heparin improve live birth rates in pregnant women with thrombophilic disorders? A systematic review

INTRODUCTION Pregnancies in women with thrombophilia are associated with a higher risk of obstetric complications. We systematically reviewed the findings of relevant randomised controlled trials (RCTs) with the aim of investigating the effectiveness of low-molecular-weight heparins (LMWHs) in pregnant women with inherited thrombophilic disorders and its effect on the incidence of live births in these patients. METHODS The MEDLINE-PubMed and Cochrane CENTRAL databases from 2000 to 2010 were searched using a combination of keywords, including low-molecular-weight heparin, enoxaparin, pregnancy, live birth and thrombophilia. Studies were included if they were RCTs assessing the effect of anticoagulant treatment on live birth rates in women with a history of miscarriage without apparent causes other than thrombophilic disorder. Interventions included LMWH, with or without aspirin, aspirin alone or placebo controlled for the prevention of adverse pregnancy outcome. RESULTS 43 articles with seven RCTs were retrieved following the initial search, of which four studies had to be excluded as they assessed thromboembolic events as the final outcome (n = 1), focused on idiopathic recurrent miscarriages (n = 1), compared efficacy and safety of two doses of enoxaparin (n = 1), and examined patients with or without thrombophilic disorder (n = 1). Pooled data from the remaining three RCTs showed no significant difference in the improvement of live birth rates following LMWH interventions (p = 0.15). CONCLUSION At present, the use of LMWH in women with inherited thrombophilia with recurrent pregnancy loss is not indicated. Large randomised placebo-controlled trials are further needed to prove the effectiveness of LMWH in these patients.