Women with PCE represent a treatment-resistant phenotype in whom the endometrial inflammatory and immune status remains abnormal despite antibiotic therapy. GnRH agonist pretreatment may be most beneficial in endometrial phenotypes marked by persistent or residual inflammatory impairment rather than in all frozen embryo transfer populations.We therefore conducted a single-center prospective cohort study to investigate whether GnRH-HRT, compared with non-GnRH-based preparations, improve clinical pregnancy and live birth in women with PCE undergoing FET,