Endometrial receptivity array (ERA).

What is endometrial receptivity array?

Endometrial receptivity array (ERA) is a test that claims to find the optimal time for an embryo to be transferred into a woman’s uterus for the embryo to implant, known as the window of implantation. ERA involves taking a biopsy of  the endometrial lining of the uterus and testing the tissue to see which genes are expressed.

When combined with a computational predictor these results indicate when the endometrium may be most receptive to an embryo implanting. The endometrium will be categorised as either receptive, pre-receptive, or post-receptive. In subsequent cycles of treatment, the patient will then have what is termed a ‘personalised embryo transfer’, taking place at the optimal time for her specific window of implantation. This would theoretically increase the chances of the embryo implanting successfully and the patient having a baby. However, there is a question over whether a patient has the same window of implantation for each of their cycles of treatment.

Risks of endometrial receptivity array

As this procedure requires obtaining a biopsy of the endometrium patients can experience cramping and there is a small risk of infection and bleeding. There is also a very small chance of uterine perforation. The biopsy may need to be repeated in the rare event that either the results are inconclusive, or the biopsy fails to obtain a sufficient quantity or quality of tissue for testing.

ERA requires patients to undergo a freeze-all cycle which carries a small risk that any frozen embryos would not survive the thawing process. ERA does not carry any additional known risks for the child born as a result of fertility treatment.


One RCT has been performed to study the effectiveness of ERA at increasing a patient’s chances of having a baby. The outcomes of the study were promising but the results did not prove that ERA made a true difference to the patient’s chances of having a baby and we can’t be certain of their reliability.

Current HFEA grading

For more information, please visit the HFEA website

Your next step.

When you are ready and the time is right for you, the next step is to contact us and we will help you arrange a face-to-face, telephone or video-call introduction with one of our consultants.

You can do this by filling in the contact form below or by giving one of our friendly team a call on +44 (0) 203 263 6025 or emailing us at admin@ariafertility.co.uk.