The role of immune regulation and immunomodulation of the endometrium in the prevention of recurrent implantation disorders and miscarriages

Abstract

Infertility affects 8 to 12% of couples in the world who are of reproductive age; of these, half seek medical help, and the other 22% undergo fertility treat­ments. An annual total of ART cycles are con­duc­ted because to the rising prevalence of infertility; 15% of patients have repeated implantation failures. As reported by ESHRE in 2018, the live birth rate (LBR) at the third attempt was 20.3% and 17.2% at the fourth attempt [1,2]. Human implantation is a three-stage process, in­clu­ding apposition, adhesion, and invasion. During the apposition phase, the blastocyst contacts the endometrium, mediated by adhesion molecules. The endometrium undergoes changes to prepare for im­plan­tation, providing nutrients and support. The ap­po­sition and adhesion phase is crucial for successful implantation. Invasion occurs during the adhesion phase of implantation, where the blastocyst interacts with the endometrial surface, triggering inflammatory-like res­ponses. This interaction triggers a cascade of events, including cytokines and chemokines, leading to the attachment of the blastocyst to the endo­met­rium. This inflammatory response prepares for human invasion, involving the formation of endo­vascular extravillous trophoblasts (EVTs).