Personalized embryo transfer reduces success rates because endometrial receptivity analysis fails to accurately identify the window of implantation

Abstract

After more than a decade of increasingly widespread clinical use, personalized embryo transfer guided by endometrial receptivity analysis (ERA) remains controversial and unproven. One key element missing from the historical literature is the recognition that potential benefits from personalized embryo transfer are entirely dependent on the accuracy and predictive value of the ERA test. Results from the first comprehensive clinical trial, designed in a way that allowed independent evaluation of both potential benefits of personalized embryo transfer and the predictive value of the ERA test upon which it is based, were recently published. However, the authors failed to conduct an appropriate analysis or recognize the significance of their results. Here, we present a simple reanalysis of data from this otherwise excellent randomized controlled trial, demonstrating for the first time that the ERA was unable to identify the window of implantation as purported and that, as a result, personalized embryo transfer based on the ERA actually reduced rather than increased the birth rates. Based on these results and the lack of any contradictory evidence, it is our opinion that all clinical use of ERA-guided personalized embryo transfer should be discontinued immediately, outside of a controlled experimental setting with appropriate informed consent of all participating patients.

Keywords: in vitro fertilization; endometrial receptivity analysis; personalized embryo transfer; repeated implantation failure; window of implantation.