Endometrial Receptivity Analysis (ERA)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

ERA (Endometrial Receptivity Analysis) is a molecular diagnostic test that analyzes gene expression in an endometrial biopsy sample to estimate the personalized timing of the window of implantation (WOI): the period during which the endometrium is receptive to embryo implantation. The test analyzes the expression profile of several hundred genes. Based on results, the laboratory classifies the sample as receptive, pre-receptive, or post-receptive and recommends adjusted embryo transfer timing.¹²

ERA is used in the context of IVF frozen embryo transfer. The premise is that some women have a displaced WOI, meaning the standard transfer timing does not align with peak endometrial receptivity, and that personalizing the timing will improve live birth rates.

The published RCT evidence does not support that premise for unselected IVF patients. A randomized clinical trial published in JAMA (2022) compared receptivity-timed transfer against standard timing in 767 patients. Live birth occurred in 58.5% of the ERA-timed group versus 61.9% in the standard-timing group. The difference was not statistically significant (rate ratio 0.95; 95% CI, 0.79 to 1.13). ERA-guided timing did not improve live birth outcomes.³

An earlier observational study (ref-25) reported improved outcomes in a retrospective cohort with recurrent implantation failure. Observational findings in selected populations cannot establish that ERA works for the broader population of IVF patients. The RCT is the higher-quality evidence.⁴

ERA does not assess the underlying causes of implantation failure. It evaluates endometrial gene expression at a single time point and proposes a timing adjustment. ERA does not identify or treat the conditions that directly impair implantation: chronic endometritis, adenomyosis, submucosal fibroids, and polyps. Root-cause evaluation of implantation failure requires a different workup.⁵

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.