Confounding Factors of Chronic Endometritis in Women With Reproductive Failure

Inclusion criteria: 1. Age 20-45 years; 2. Women with a history of 2 or more consecutive miscarriages before 24 weeks of gestation12; or 3. Women who failed to conceive after unprotected intercourse for one year; or 4. Women who failed failure to achieve a clinical pregnancy after two consecutive cycles of IVF, ICSI or frozen embryo replacement cycles where the cumulative number of transferred embryos is no less than four for day-2 embryos and no less than 2 for day-5 embryos (blastocysts), with all embryos being of good quality. Exclusion criteria 1. Uncorrected uterine anomalies, such as the septate or bicornuate uterus, fibroids (submucous/intramural); 2. Untreated hydrosalpinx; 3. History of antiphospholipid syndrome; 4. Known clinical autoimmune disease; 5. Undergoing immunotherapy; 6. Abnormal thyroid function; 7. Abnormal karyotyping. 8. Those with active pelvic inflammatory disease or suspicion of infection etc.