Biomarkers for Endometrial Receptivity: Implications for Infertility, Implantation Failure, and Advances in Diagnosis and Treatment.

Female infertility affects millions of women worldwide and is frequently caused by ovulatory disorders and uterine pathologies. Among these, endometrial abnormalities play a central role, especially in cases of embryo implantation failure during assisted reproductive techniques (ARTs). Endometrial receptivity, the period during which the endometrium prepares to receive and support embryo implantation, is a complex process regulated by essential morphological, molecular, and immunological changes necessary for a successful pregnancy. This review examines the mechanisms that govern endometrial receptivity and investigates the dysfunctions that may compromise this phase. In particular, it focuses on key biomarkers of receptivity, such as estrogen receptor-alpha (ERα), integrins, and uterine immune cells, which are crucial for endometrial preparation. It provides an in-depth understanding of female reproductive physiology and the main indicators to optimize embryo transfer at the most opportune time during the menstrual cycle within medically assisted reproductive techniques. Furthermore, it explores innovative approaches, such as immunomodulation and mesenchymal stem cell therapy, which are opening new diagnostic and therapeutic horizons, offering hope to many couples facing reproductive challenges.