ERA Test — Finding Your Personal Implantation Window

Standard IVF protocols assume the uterine lining becomes receptive to an embryo on a predictable day — typically after 5 full days of progesterone exposure (for a day-5 blastocyst transfer). For most women, this timing works. For roughly 25–30%, it doesn’t — their personal implantation window is shifted forward or backward by a day or more. The ERA test identifies this shift, and adjusting transfer timing accordingly can turn repeated failure into success.

What the ERA Actually Does

ERA — Endometrial Receptivity Analysis — is an endometrial biopsy performed during a mock cycle (no embryo transferred). A thin catheter takes a small tissue sample from the uterine lining on the day a transfer would have occurred. The tissue is analysed for expression of 248 genes known to define the receptive state. The result:

• Receptive: your window matches the standard protocol timing — the cause of failure lies elsewhere.
• Pre-receptive: your window opens later than standard — the embryo was being placed too early. Transfer should be delayed (usually by 12–24 hours of additional progesterone).
• Post-receptive: your window opens earlier — transfer timing should advance. Less common.

Who Should Consider It

Primary indication: recurrent implantation failure — two or more transfers of good-quality (ideally PGT-normal) embryos that didn’t implant. If the embryos were chromosomally normal and the lining looked adequate on ultrasound, timing mismatch becomes a leading suspect.

Not recommended as routine for first cycles. Most women are receptive on the standard day, so testing everyone adds cost (₹25,000–40,000) and delays treatment by a cycle without improving outcomes for the majority. It earns its value specifically when standard timing has failed.

The Mock Cycle Process

You undergo lining preparation exactly as you would for a frozen transfer — either natural or medicated protocol. On the standard transfer day, instead of a transfer, a 30-second endometrial biopsy is performed (expect cramping similar to an IUD insertion — brief and manageable). The sample is shipped to the testing lab; results return in 2–3 weeks. Your next FET is then timed to your personalised window.

Does It Work?

Initial studies showed striking improvements — personalised timing raised implantation rates by 25–50% in previously failing patients. Larger, more recent studies are more nuanced: the benefit appears genuine for women with displaced windows (roughly a quarter of those tested) but not for those already receptive. Translation: the ERA helps when timing is the problem, and doesn’t when it isn’t — which is exactly how a diagnostic test should work. The value is in patient selection, not universal application.

Cost and Practical Notes

₹25,000–₹40,000 including biopsy, shipping, and genomic analysis. The mock cycle itself adds one month before the actual transfer. Most clinics combine ERA with other endometrial tests (EMMA, ALICE — assessing microbiome and infection) in a single biopsy, maximising the diagnostic yield of one procedure.

If you’ve had two good embryos fail to implant and nobody has mentioned ERA, bring it up. Post-failure review guide · Ask Pregology