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

ABSTRACT

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.