#113 : Transdermal Oestrogen (GEL) for Endometrial Preparation in Frozen-Thawed Embryo Transfer

Abstract

Background and Aims: Frozen-thawed embryo transfer (FET) requires a synchronization between endometrium and embryo. Pregnancy and live birth rates are proven to be significantly higher with FET due to better endometrial receptivity. In this study, we look at effectiveness oftwo oestrogen preparations in hormone replacement therapy (HRT) FET cycle on the pregnancy outcomes. Method: This is a retrospective analysis of 200 HRT FET cycles from 1st Jan 2020-31st December 2021, divided into 2 groups. Group 1 (n=100) received T Progynova 6 mg/day and Group 2 (n=100) received Oestrogel 6 mg/day (17B oestradiol 0.06% gel Besins France) starting on day 1 of menses, without GnRH agonist pituitary downregulation. The oestrogen dose was adjusted accordingly to achieve endometrial thickness (ET) of minimum 8 mm, prior to initiation of vaginal progesterone. The pregnancy outcomes (biochemical pregnancy, clinical pregnancy, ongoing pregnancy, early pregnancy loss and ectopic pregnancy rates), duration of oestrogen usage and endometrial thickness measurement prior to embryo transfer were analysed. Results: The biochemical pregnancy rate in this study was 39%, with a clinical pregnancy rate of 31%. Comparing both preparations, the biochemical pregnancy rate (p=0.562), clinical pregnancy rate (p=0.705), ongoing pregnancy rate (p=0.623), and early pregnancy loss rate (p=0.705) were not statistically significant. The duration required to achieve optimal endometrial thickness (p=0.212), and endometrial thickness measurement prior to vaginal progesterone commencement (p=0.335) were comparable. Conclusion: Oestrogel is a non-inferior option to oestradiol valerate for endometrial preparation in HRT FET cycles, especially for patients with high risk of venous thromboembolism due to its safety profile.