Clinical Research Directory

Inclusion Criteria: * Reproductive failure with abnormal endometrial natural killer (NK) cells in menstrual blood; * With a clear intention to conceive; * Normal ovarian function, or premature ovarian insufficiency with ≥2 high-quality cryopreserved embryos available for transfer; * Endometrial thickness measured by transvaginal ultrasound during the periovulatory period ≥7 mm; * Body mass index (BMI) between 18 kg/m² and 28 kg/m²; * Willing to comply with the follow-up plan of this study. Exclusion Criteria: * Use of progesterone receptor modulators; * One of the couple's chromosomal karyotype abnormalities, with no euploid embryo identified via preimplantation genetic testing for aneuploidy; * Severe endometriosis or adenomyosis, uterine fibroids affecting uterine cavity morphology, uterine malformations, intrauterine adhesions, or thin endometrium; * Uncontrolled autoimmune or endocrine disorders; * Contraindications to pregnancy; * History of malignant tumors; * Participating in other clinical studies; * Allergy to blood products.