Effects of oral and transdermal estrogen on postoperative endometrial recovery after missed abortion: a retrospective longitudinal cohort study

Abstract

Background: Missed abortion is a common complication of early pregnancy, and surgical evacuation remains the primary treatment. This study aims to evaluate the effects of no estrogen, oral estrogen, and transdermal estrogen on postoperative endometrial recovery and long-term reproductive outcomes. Methods: This retrospective longitudinal cohort study included women with early missed abortion who underwent surgical evacuation at Chengdu Women’s and Children’s Central Hospital between June 2023 and May 2025. Patients were stratified into three groups: no-estrogen, oral estrogen, and transdermal estrogen. Clinical data were collected at five time points: perioperative period, 1 week postoperatively, 1 month postoperatively, 3 months postoperatively, and 1 year postoperatively. Primary outcomes were endometrial thickness, intrauterine adhesion, adverse reactions, and 1-year pregnancy outcomes. Statistical analyses comprised the t-test, the chi-square test, the binary logistic regression analysis, and the multiple linear regression analysis. Results: A total of 561 women were included. Endometrial thickness at 1 and 3 months was significantly greater in both estrogen groups compared with the no-estrogen group (p < 0.001 and p = 0.001, respectively), with the transdermal group showing the highest values. Reduced menstrual flow was less frequent in the estrogen groups (p = 0.022). Oral estrogen was associated with higher rates of breast tenderness and systemic symptoms, whereas transdermal estrogen demonstrated superior adherence (68.3% vs. 46.7%, p < 0.001). At 1-year follow-up, pregnancy outcomes did not differ significantly across groups (p = 0.819), although higher conception rates were observed in the estrogen groups, particularly among those receiving transdermal therapy. Conclusion: Postoperative estrogen therapy promotes endometrial recovery after the surgical treatment of missed abortion. Both oral and transdermal estrogen treatments were effective, but transdermal administration provided better tolerability and adherence. Estrogen use may improve reproductive prognosis, warranting further prospective studies to confirm these findings.