The impact of regressed endometrial hyperplasia on reproductive outcomes following frozen embryo transfer: a propensity score-matched cohort study

Purpose: To investigate the impact of regressed endometrial hyperplasia (EH) on assisted reproductive technology outcomes, particularly in comparison with infertile women with a relatively normal endometrium. Methods: This retrospective study included 95 patients with EH regression after conservative treatment and 30634 infertile controls at the Reproductive Medicine Center from January 2015 to December 2022. Propensity score matching was performed at a ratio of 1:4 between EH and control patients following first frozen embryo transfer. Pregnancy, obstetric and neonatal outcomes were compared between matched pairs. Subgroup analysis was performed between EH patients with and without atypia. Binary logistic regression was conducted to identify risk factors for live birth among EH patients. The primary outcome was live birth rate. Results: = 0.046). Subgroup analysis demonstrated a marginally lower live birth rate in EH patients with atypia compared with those without atypia. Furthermore, logistic regression analysis confirmed that EH with atypia, prolonged progesterone treatment and delayed remission associated with reduced likelihood of live birth. Conclusions: Even after complete remission, EH remained associated with a reduced likelihood of live birth following FET. Prolonged progesterone therapy and delayed remission further diminished the live birth likelihood, highlighting the need for optimized treatment and individualized conception counseling in this high-risk population.