Abstract: Objective：To compare the effects of natural cycle (NC) and hormone replacement therapy (HRT) cycle on the expressions of endometrial progesterone receptor (PR) and integrin αⅤβ3 in patients with Repeated Implantation Failure (RIF), so as to explore the effects of these two endometrial preparation regimens on the endometrial receptivity during the implantation window. Methods: The endometrial specimens during mid-luteal phase were collected from 25 patients with NC cycle and 18 patients with HRT cycle. The expression levels of integrin αⅤβ3 and PR were detected by immunohistochemical method. Results: There were no significant differences in the mean H-scores of PR and integrin αⅤβ3 expression in endometrial glandular epithelial cells, and PR expression in stromal cells, between the NC regimen group and the HRT regimen group (P＞0.05). Conclusions: There are no significant differences in the effects of NC regimen and HRT regimen on the endometrial receptivity during the implantation window, suggesting that these two endometrial preparation protocols are suitable for patients with RIF.

Key words: Embryo implantation, Ovulation induction, Hormone replacement therapy, Receptors, progesterone, Repeated implantation failure, Natural cycle, Integrin alphaⅤbeta3