A Comparison of the Effects of Transdermal Estradiol and Estradiol Valerate on Endometrial Receptivity in Frozen-thawed Embryo Transfer Cycles: A Randomized Clinical Trial

Background: The purpose of this study was to determine the optimal endometrial preparation protocol by comparing the clinical outcome of two methods of endometrial preparation in frozen-thawed embryo transfer (FET) cycles, including that is, oral estradiol and 17ß-estradiol transdermal patch. Methods: In this randomized controlled trial, women underwent either conventional IVF or intracytoplasmic sperm injection (ICSI) who had at least two top-quality embryos appropriate for cryopreservation and frozen embryos from previous cycles. In the study group (n=45), 17-B estradiol transdermal patches 100 μg were applied from the second day of the cycle and continued every other day. Then, each patch was removed after four days. In the control group (n=45), oral estradiol valerate 6 mg was started at the same time and continued daily. Results: There was a significant difference in estradiol level on the day of progesterone administration and the day of embryo transfer between the two groups (p= 0.001 in both), but no significant difference was observed between them in biochemical and clinical pregnancy rates (32.6% vs. 33.3%, p=1.000 and 30.2% vs. 33.3%, p=0.810, respectively). Conclusion: It is suggested that estradiol transdermal patches be used instead of oral estradiol in FET cycles. Due to the reduced costs, drug dose, and emotional stress as well as the simplicity of the protocol for patients.