A randomized clinical trial of transdermal (gel) versus oral estrogen for endometrial preparation in frozen embryo transfer cycle

Abstract

We conducted a prospective randomized clinical trial of women undergoing treatment for cryopreserved embryo transfer to compare two EP protocols: estrogen gel and estrogen pills.This was a single-center study conducted at a private reproductive center between June 2020 and October 2021. The study was approved by the Ethics Committee for Research in Humans of the Santa Casa of Sao Paulo School of Medical Science (Process number 23023219.2.0000.5479) in accordance with good clinical practice guidelines. Patients signed the informed consent form agreeing with the assisted reproduction treatment procedures according to local ethics regulations. It was also registered at the Registro Brasileiro de Ensaios Clínicos (ReBEC-Brazilian Clinical Trials Registry) under UTN (Universal Trial Number): A36950145802.The study's inclusion criteria were as follows: women aged ≥21 and ≤38 years when undergoing embryo transfer using