Objective  To investigate the efficacy and pregnancy outcomes of fertility-sparing therapy for atypical endometrial hyperplasia (AEH) and stage IA endometrial carcinoma (EC).

  Methods  A retrospective analysis of the clinical data of 119 patients with AEH and IA EC who had undergone fertility preservation treatment at Beijing Obstetrics and Gynecology Hospital between January 2010 and December 2020 was performed. The patients were assigned into an AEH group (92 cases) and an EC group (27 cases). Data on the remission rate, pregnancy, and recurrence after treatment were analyzed.

  Results  The complete response (CR) rate was 93.5%（86/92）in the AEH group and 77.8% (21/27) in the EC group. The curative effect was better in the AEH group than in the EC group (P=0.017). After achieving CR, 64 patients had fertility requirements. The pregnancy rate was 39.1% (25/64), and the delivery rate was 31.3% (20/64). The assisted reproductive technology (ART) group had higher pregnancy (P=0.007) and delivery (P=0.009) rates than the natural conception group. The influence of age, pathological type, complications, weight, manner of conception, treatment time, and intrauterine adhesionon on the success of pregnancy was further analyzed, showing that the manner of conception was an independent factor for the success of pregnancy (P=0.013). The pregnancy rate of the patients who chose ART was 5.237 times higher than that of patients who chose natural conception. Until the end of follow-up period, the recurrence rate was 24.3% (26/107), the median recurrence time was 34 (9–96) months, and the 5-year recurrence free survival rate was 78.5% (23/107).

  Conclusions  There is a high frequency of remission among patients with AEH and stage IA EC, enabling them to enjoy a successful pregnancy and delivery after fertility-sparing treatment. However, after reaching CR, it is recommended that ART be adopted to improve the pregnancy and delivery rates. The disease may recur and therefore close monitoring and follow-up are indicated.