The Impact of Uterine Immunity and Its Alterations on the Embryo Implantation Process

Inclusion Criteria: Female patients aged \>18 and \<43 years at the time of embryo transfer. Transfer of cryopreserved embryos diagnosed as euploid through preimplantation genetic testing for aneuploidy (PGT-A). Embryo transfer performed at the blastocyst stage. Exclusion Criteria: Patients with an intrauterine device (IUD) in situ within the three months prior to study enrollment. Presence of autoimmune diseases and/or ongoing treatment with corticosteroids. Structural or pathological abnormalities of the uterine cavity, including but not limited to polyps, intramural myomas measuring 2-4 cm, submucosal fibroids, uterine septum, or hydrosalpinx, identified during study participation. Patients with a history of these conditions may be included if the pathology has been resolved prior to the initiation of any study-related procedures or sample collection. Presence of severe or uncontrolled fungal or viral infections which, in the opinion of the principal investigator, may compromise the patient's ability to participate or affect the integrity of study outcomes. Any medical condition or illness that is unstable, poses a potential risk to patient safety, or may interfere with adherence to the study protocol. Patients lacking a confirmed preimplantation genetic diagnosis of euploidy. Patients with a clinical diagnosis of endometriosis or adenomyosis.