Unlocking the WOI wonder:
ER Map® empowers personalized endometrial receptivity


Recent controversies have cast doubt on the credibility of endometrial receptivity essays, which play a pivotal role in the successful embryonic implantation. The human endometrium is an amazing structure that goes through changes during the menstrual cycle to create a receptive state for the embryo. This special period, known as the window of implantation (WOI), is when the endometrium shows specific gene expression patterns that indicate its receptivity.

Now, here’s where things get interesting – we have an incredible molecular tool called ER Map® that can accurately predict the endometrial receptivity status through transcriptomic analysis. With ER Map®, we can precisely determine the WOI, allowing for a personalized embryo transfer.

En definitiva, el test ER Map® permite identificar el momento óptimo del endometrio para transferir el embrión, es decir, definir exactamente cuándo hay más probabilidades de embarazo.

What sets ER Map® apart from other tools for studying endometrial receptivity?


ER Map® is a highly optimized tool, specifically designed to target 40 genes that play crucial roles in endometrial receptivity and the immune response. These genes are unique to the endometrium and have been extensively studied for their involvement in the process of endometrial proliferation, receptivity and embryonic implantation.


When it comes to gene expression analysis, ER Map® uses high-throughput RT-qPCR, the most accurate and reliable technique currently available. This validated technique is considered the gold standard for gene expression analyses, avoiding limitations in the ranges of detection, and affections in background hybridization and probe saturation processes.


ER Map® approach to WOI identification guarantees a personalised determination of the best time for embryo transfer. While other tools determine the optimal implantation stage using a statistical estimation with an associated significant error, ERMap® takes into account the unique characteristics of each patient’s endometrium and confirms each patient receptivity period minimising diagnostic error.


ER Map® has been proven to be highly reproducible. Results from double analysis of biopsies within the same patient and improved outcomes in assisted reproductive treatment (ART) and in-vitro fertilization treatments (IVF) when transfers were performed within the WOI, as identified by ER Map®, demonstrate its reliability.

Successful results

Studies have shown that when ER Map® is used for personalized embryo transfer guidance, pregnancy rates may increase by 21%. That’s a significant improvement, reducing the probability of pregnancy loss by half! 


ER Map® with the high accuracy determines the correct timing of the WOI, which is crucial for maximizing ART and IVF outcomes. Even a deviation of just 12 hours from the WOI in the embryo transfer schedule can negatively impact the results, highlighting the importance of precise timing.

Wide-Range Indications

ER Map® isn’t just beneficial for patients with implantation failure – it also helps those experiencing recurrent miscarriage. Many studies show that precise assessment of endometrial receptivity can improve ART and IVF results, whether with own oocytes, or egg donation, with or without PGT-A.



Amidst the recent discussions surrounding endometrial receptivity essays in scientific and medical publications, IGLS would like to emphasize that the overall credibility of endometrial receptivity studies should not be undermined based on findings related to specific tools. It’s important to recognize that while all endometrial studies aim to determine the window of implantation (WOI), different techniques may yield varying results. Considering the characteristics mentioned above, we maintain our belief that ER Map® continues to be a reliable and precise tool for ART professionals.

Endometrial Receptivity Map