Comparing FET Guided by ERA Vs Standard Timing in Patients with Recurrent Implantation Failure

The pregnancy rate of in vitro fertilisation (IVF) remains around 35% per transfer. Women who are not pregnant following several embryo transfers are regarded as having recurrent implantation failure (RIF), with one of the causes being the asynchronization of the embryo and endometrium. Endometrial receptivity analysis (ERA) may identify the window of implantation and guide the timing of embryo transfer to improve the pregnancy outcomes. However, there is no randomized controlled trial on the clinical effectiveness of ERA in women with RIF. This is a multicenter double-blind randomized controlled trial. All participants will have an endometrial biopsy for ERA in a standard hormonal treatment cycle. They will then be randomly assigned in the central laboratory into the intervention or control group in a 1:1 ratio. At the transfer cycle, participants in the intervention group will have frozen embryo transfer timed according to the results of ERA while those in the control group will have the transfer according to the standard timing. The primary outcome is the ongoing pregnancy rate at 10-12 weeks at their first frozen embryo transfer.