What Is ERA?
ERA (Endometrial Receptivity Analysis) is a tool to find the optimal time for embryo transfer. The embryo is able to implant in a specific receptive period of time during a woman’s cycle. This is called the window of implantation(WOI). The likelihood of implantation could be increased by transferring embryos during this period.
After taking progesterone, the endometrium will open WOI, and transfer embryos during this period could get successful implantation.
How Does ERA Predict Optimal WOI?
The human endometrium is a dynamic organ that undergoes cyclic changes in response to hormones. Each endometrial cycle stage (proliferative phase, pre-receptive phase, receptive phase, and post-receptive phase) shows different Endometrial Receptivity Array (ERA) gene expression profiles. This ERA uses next-generation sequencing (NGS) to analyze 248 genes related to endometrial receptivity and compares big data with machine learning to give the results so that every woman can use the gene expression profiles to find her own unique WOI.
How To Interpret The ERA Report?
ERA reports can be divided into three types of results (table 1):
Receptive: shows that your window of implantation is the same day as when the sample was taken and the recommendation is to proceed with embryo transfer, under the same conditions as for biopsy.
Or, by contrast, a non-receptive result that shows that your biopsy was taken outside of your window of implantation. It can include a Pre or a Post-Receptive state.
Post receptive means that the sampling result has exceeded the time of opening the implantation window (the window is closed), and shortening the time of taking progesterone is the optimal time for the embryo transfer. To confirm this result, the analysis of a second biopsy on the recommended day is needed.
Pre-receptive means that the sampling result has not yet reached the time of opening the implantation window (the window is not yet open), and prolonging the time of taking progesterone is the best time for the embryo transfer. In around 5% of cases (when this displacement implies 2 days) a new endometrial biopsy is required for validation.
