Recurrent Implantation Failure and Low Molecular Weight Heparin

Abstract

Implantation of the embryo into the endometrium is the first step in the establishment of pregnancy. This process is complex, and depends on many factors. Recurrent implantation failure is a source of distress to patients and specialists. It is defined as failure to achieve a viable pregnancy, following ">3 embryo transfers with high quality embryos or the transfer of ≥ 10 embryos in multiple transfers". Thrombophilic conditions that contribute to recurrent implantation failure are the main concern in this review. The mechanism of implantation failure is believed to be due to decreased blood flow to the endometrium and placenta which can hinder normal endometrial receptivity leading to miscarriage. Defects in early placentation resulting in pregnancy failure, have focused attention on the therapeutic potential of low molecular weight heparin in the implantation process. Heparin has a role at all stages of implantation to improve pregnancy outcomes. There are controversies in literature regarding the association between thrombophilia and recurrent implantation failure and available literature regarding this issue is very heterogeneous. Various investigators, have shown that women with RIF are more likely to have a thrombophilia disorder, yet a clear cause cannot be acknowledged from these studies. Heparin treatment has been evaluated in several studies, showing conflicting evidence. However, several studies have pointed out that it may play a role in a subset of patients who presents a thrombophilia mutation, thus the group of patients that might benefit is needed to be identified. This review is dedicated to evaluate the published literature about the role of low molecular weight heparin in case of recurrent implantation failure with or without the presence of thrombophilia.

Co‐administration of tacrolimus and low molecular weight heparin in patients with a history of implantation failure and elevated peripheral blood natural killer cell proportion

“…Low‐molecular‐weight heparin (LMWH) originates from heparin by chemical or enzymatic depolymerization. LMWH can promote embryo implantation, prevent spontaneous abortion, and improve the clinical pregnancy outcome of those with RIF 17,18 . Although LMWH is safe and effective for patients, applying LMWH to patients with a history of implantation failure and high pNK cell proportion can improve clinical outcomes, extensive studies are still required.…”

Современные Подходы К Лечению Беременных С Генетической Предрасположенностью К Тромбофилии: Обзор Литературы

“…Есть основания считать, что антикоагулянтная терапия гепарином может быть эффективной у женщин с ПНБ [31], однако при этом показано, что терапия аспирином и/ или гепарином без тестирования на маркеры тромбофилии не помогает улучшить исходы беременности у этих пациенток. Имеются сведения, что гепарин улучшает имплантацию за счет восстановления нарушенной инвазии и дифференцировки трофобласта и предотвращения активации комплемента из-за его структурного сходства с гепарансульфатом, молекулой, играющей важную роль в процессах репродукции [32].…”