Effect of LMWH on Pregnancy Outcome in Women With Multiple Failures of IVF-ET

Low-Molecular-Weight-Heparin (LMWH) has been used empirically in patients undergoing in-vitro fertilization embryo transfer (IVF-ET) with the purpose to aid in improving pregnancy outcomes. The potential mechanism is that LMWH could exert its anticoagulant effect by inhibiting factor Xa, reducing the risk of insufficiency blood supply in the very early stage of pregnancy. Moreover, LMWH is supposed to play a role in manipulating blastocyst supposition, adhesion, and implantation, as well as trophoblast differentiation and invasion. However, limited high-quality clinical trials focus on the effectivity of LMWH in IVF-ET, and the published evidence is not consensus, leading to considerable controversy in the clinical application of LMWH in IVF-ET patients. Here, investigators try to evaluate the effect of LMWH on pregnancy outcome in women with multiple failures of IVF-ET via a multi-center randomized controlled trial.