Two Methods of Endometrial Preparation (Hormonal Replacement Therapy and Ovarian Stimulation) in Patients Undergoing Frozen Embryo Transfer Cycle: A Randomized Clinical Trial

Document Type : Original Article

Authors

1 Fellowship of Infertility, Nical Research Development Center, Faculty of Medicine, Shahid Beheshti University Medical Science, Tehran, Iran.

2 Assistante Professor, Department of Obstetrics and Gynecology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

10.22038/ijogi.2025.85183.6314

Abstract

Introduction: Currently, there are several protocols for endometrial preparation in patients undergoing frozen embryo transfer, including ovulation induction, natural cycle, hormone therapy, and other methods. Each of these methods has its own advantages and disadvantages. Accordingly, the present study was conducted with aim to evaluate and compare the effect of these two methods on pregnancy outcomes in patients undergoing frozen embryo transfer.
Methods: This single-blind clinical trial study was conducted in 2023-2024 on 208 patients who were treated for infertility at the Mahdieh Hospital Clinic and whose embryos had been frozen, and therefore were candidates for a frozen embryo transfer cycle. Patients were randomly divided into two groups receiving estradiol and letrozole. After the intervention, pregnancy outcomes including clinical and chemical pregnancy, ectopic pregnancy, cycle cancellation, and miscarriage were evaluated. Data analysis was performed using SPSS statistical software (version 26) and Mann-Whitney and Chi-square tests. P<0.05 was considered significant.
Results: The percentage of clinical pregnancy, chemical pregnancy, and stable pregnancy was higher in the hormone replacement therapy group than in the ovarian stimulation group, but this difference was not statistically significant (p>0.05). In contrast, the mean time required for endometrial preparation in the letrozole group was significantly longer than in the estradiol group (p<0.001). Also, a statistically significant difference was observed between the two groups in variables related to ovarian stimulation (including weak, normal and polycystic) (p<0.001).
Conclusion: There was no significant difference in pregnancy outcomes between the two methods of hormone replacement therapy and ovarian stimulation; however, the duration of endometrial preparation was significantly longer in the letrozole group. The choice of treatment protocol can be made based on the individual patient's condition and clinical considerations.

Keywords

Main Subjects

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The Iranian Journal of Obstetrics, Gynecology and Infertility
Volume 28, Issue 5
July 2025
Pages 29-37

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