Clinical Outcomes of Oral vs. Transdermal Estrogen for Endometrial Preparation for Frozen Thawed Embryo Transfer in HRT-FET Cycles: A Systematic Review and Meta-Analysis

Abstract

Background and Purpose: Among different routes of estrogen formulations, the transdermal route has obtained popularity in recent years for endometrial preparation in hormone replacement (HRT) frozen embryo transfer (FET) cycles. However, no clear evidence is available regarding clinical outcome of the transdermal route. This meta-analysis investigated the clinical outcomes of oral versus transdermal estrogen for endometrial preparation for FET in HRT-FET cycles. Methods: A comprehensive literature search was performed for all published randomized controlled trials (RCTs) before May 30, 2022, in electronic databases, including PubMed, Cochrane Library, Embase, CINAHL, Trip Database, Worldwide Science, and Google Scholar. Outcomes, including endometrial thickness, implantation rate (IR), miscarriage rate (MR), clinical pregnancy rate (CPR), and live birth rate (LBR), were measured using pooled odds ratio (OR) or standardized mean difference (SMD) with 95% confidence intervals (CIs). Results: Seven studies involving a total of 898 IVF patients were included in the meta-analysis. In a pooled analysis, endometrial thickness (ET) was more in the transdermal group as compared to the oral estrogen group ([Formula: see text]; 95% [Formula: see text]–0.31). However, no significant association for IR ([Formula: see text]; 95% [Formula: see text]–1.38), CPR ([Formula: see text]; 95% [Formula: see text]–1.31), MR ([Formula: see text]; 95% [Formula: see text]–2.06), and LBR ([Formula: see text]; 95% [Formula: see text]–1.23) was found between oral versus transdermal estrogen groups. Conclusions: In HRT-FET cycles using oral or transdermal estrogen, no significant difference was seen in clinical outcomes of IR, CPR, and LBR rates; however, a trend for a higher endometrial thickness was noted in the transdermal group.