Efficacy of a Non-Invasive Endometrial Receptivity Prediction Model Based on Peripheral Blood miRNA Signatures During the Peri-Implantation Period in Improving IVF Outcomes in Patients With Unexplained RIF

Inclusion Criteria

• •1. Patients with unexplained recurrent implantation failure (RIF) meeting the diagnostic criteria for RIF: adult women under 40 years old who have failed to achieve clinical pregnancy after 3 embryo transfer cycles; or after transferring at least 3 high-quality embryos.
• •Definition of high-quality embryos: Day 3 embryos (with a cell count ≥7 and fragmentation rate \<10%) and blastocysts (≥3BB).
• •2. Female BMI: 18.5-25 kg/m².
• •3. Endometrial thickness ≥7 mm during the embryo transfer cycle.
• •4. Women planning to undergo frozen-thawed embryo transfer (FET) of blastocysts following in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).
• •5. Signed informed consent form.