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The Endometrial Receptivity Array (ERA®) is an innovative diagnostic test recommended to infertile women with a history of very early pregnancy loss or recurrent implantation failure following an Assisted Reproductive Technique (ART).

The ERA® test assesses the lining of the womb (endometrium) at the molecular level, to determine the most optimal timing for implantation of the early embryo. Normally, this is around the 19th-21st day of the menstrual cycle (5-7 days after ovulation), but it can vary depending on individual circumstances.

In preparation for the arrival of the early embryo, the endometrium grows and thickens, reaching a peak of receptiveness. These few optimal days for the embryo implantation are known as the ‘implantation window’. If an early embryo (blastocyst stage) implants successfully at this point, the receptive endometrium will then form the placenta and pregnancy will proceed. However, if implantation does not happen, the highly regenerative endometrium will shed itself during your menstrual period and start its cycle again.

Here at AAFC, we use the ERA® test to establish the timing of this endometrial implantation window, as we know from experience that is a crucial factor for the success of an ART. Estimation of endometrial receptivity in the past was done with a series of ultrasound transvaginal scan. But, as the endometrium can be sometimes affected by fertility hormonal treatments, the ERA® test is a lot more reliable and sensitive to individual variation.

The test involves molecular analysis of an endometrial biopsy a month before your planned ART. The ERA® test specifically looks at 238 genetic markers relating to the status of endometrial receptivity*, and by assessing their levels determines whether the endometrium is in a pre-receptive, receptive or post-receptive phase.

The ERA® test is highly recommended to women that have previously experienced implantation failure with good quality embryos.

Additionally, women, older than 37 years of age, are also good candidates for ERA® testing. This is because the age of the mother may contribute in reduced womb receptivity, independently of an early miscarriage incident.

An endometrial biopsy for ERA® testing is performed by one of our doctors. It is normally a pain-free step that takes about 10-15 minutes to complete without the need for anesthesia or recovery time. You will be able to return to your daily activities as normally.

Depending on your individual circumstances, your doctor will determine the appropriate day of your menstrual cycle for the collection of the biopsy. That may be done either by a series of ultrasound transvaginal scans, or by a series of blood tests and hormonal level monitoring.

The biopsy will be sent off immediately to the manufacturer’s laboratory for analysis and results of your endometrial receptivity status (pre-receptive, receptive or post-receptive) will be returned to us within 5-10 business days.

A pre-receptive or post-receptive outcome will mean that your optimal endometrial receptivity does not coincide with the expected menstrual day, and in this case, we can modify your receptivity with some hormonal treatments.

Currently, unsuccessful implantation accounts for 2/3 of failed assisted reproduction cases, and the more we know on this front, the more we will be able to improve your assisted reproduction experience and your chances of becoming pregnant. With the ERA® results, embryo transfer can be planned to happen at the most optimum day of your cycle, which will favor implantation and increase your prospect to conceive.

Here in AAFC, we use the ERA® testing in conjunction with other diagnostic tests in order to bypass, persistent infertility, previous ART failure and repeated miscarriages, especially in women older than 37 years of age. Our specialist doctors can provide you with further information, consult you on all available options and offer you support when necessary.


* Ruiz-Alonso M, Blesa D, Simón C (2012). The genomics of the human endometrium. Biochim Biophys Acta.1822(12): 1931-42. (Pubmed; PMID: 22634130)