Abstract: Endometrial receptivity (ER), one of important factors related to the successful implantation of embryo, refers to the ability of endometrium to accept the embryo. Benifited from the development of assisted reproductive technology, the number of high-quality embryos has increased. However, the success rate of embryo implantation has not reached a high level. Most studies on the implantation process are focused on embryo, while the study on endometrial factors is less. It is necessary to pay attention to ER, and how to improve ER, so as to improve the embryo implantation rate and the clinical pregnancy rate. Heparin as an anticoagulant plays an important role in anticoagulant, inhibition of platelet aggregation and anti-inflammation. Heparin was also widely used in the field of obstetrics and gynecology, such as the prevention of postoperative thrombosis and recurrent abortion, and the treatment of gestational hypertension and other diseases. In addition, heparin has also been used to improve the success rate of embryo implantation in the clinical practice of reproductive medicine due to its positive effect on ER. The clinical application of heparin in reproductive medicine, as well as the mechanism related to ER, was reviewed.

Key words: Heparin, Heparin, low-molecular-weight, Cytokines, Embryo implantation, Reproductive techniques, assisted, Trophoblasts, Endometrial receptivity