The ERA (Endometrial Receptivity Analysis) test reads 248 gene markers in an endometrial biopsy to find your personal window of implantation, then schedules your embryo transfer inside that window. The best-designed trial so far found no benefit: live birth was 58.5% with ERA-guided transfer versus 61.9% with standard timing (Doyle 2022, JAMA), so ERA remains a contested add-on rather than routine care.
All figures here come from Igenomix’s official product materials, public CDC/ASRM guidance, the HFEA add-on registry, and peer-reviewed literature indexed on PubMed. The ProIVF Medical Editorial Team compiled the data and the ProIVF Medical Advisory Board reviewed it; both the supporting and opposing evidence are presented so you can decide before paying out of pocket.
What Is an ERA Test and How Does It Work?
Your uterine lining is only able to accept an embryo during a brief phase of each cycle called the window of implantation (WOI), which falls in the luteal phase. ERA measures whether your transfer date actually lands inside that window.
Traditionally, clinics time blastocyst transfer to about day 5 of progesterone exposure — a schedule built on population averages, even though individual windows differ. The ERA test addresses this by biopsying the lining during a mock transfer cycle and classifying it as:
- Receptive — the window is open right now, so standard timing works;
- Pre-receptive — the window has not opened yet; more days of progesterone are needed;
- Post-receptive — the window has already closed; progesterone should be shortened.
If the result is pre- or post-receptive, the doctor shifts the transfer date accordingly — a strategy called personalized embryo transfer (pET).
ERA was launched in 2011 by the Spanish genetics company Igenomix as the world’s first commercial endometrial receptivity test, and the company reports it is now used at more than 3,000 clinics worldwide.
What Happens During an ERA Test Cycle?
ERA is a two-phase process: a mock “test cycle” that ends in a biopsy, followed by a separate transfer cycle at the adjusted timing. You take medication in both phases.
- Step 1 — Mock transfer cycle. You follow the same protocol as a frozen embryo transfer (FET): estrogen to build the lining, then progesterone started at a set time.
- Step 2 — Endometrial biopsy. Around day 5 of progesterone — the standard transfer day — the doctor passes a thin Pipelle catheter through the cervix to collect a small strip of lining. It is an office procedure, usually without anesthesia, lasting 1–2 minutes, with brief lower-abdominal cramping for most women.
- Step 3 — Laboratory analysis. The sample goes to a lab (e.g., Igenomix), where RNA is extracted and the expression of 248 receptivity genes is compared against a transcriptomic database of more than 200,000 women, producing a receptive / pre-receptive / post-receptive result.
- Step 4 — Adjusting the timing. Per Igenomix, about 90% of women do not need a second biopsy. A pre-receptive result means progesterone is extended by 2 days in the next cycle; a post-receptive result means it is shortened.
- Step 5 — Personalized transfer (pET). The embryo is transferred in the following cycle at the adjusted time.
One Biopsy or Two?
Most patients need only one biopsy, but two result categories trigger a repeat test cycle. A pre-receptive result is re-biopsied to confirm that 2 extra days of progesterone opened the window; a post-receptive result is re-tested the same way.
Does ERA Actually Improve IVF Success Rates?
The evidence is genuinely split. The manufacturer-backed trials report large gains; the most rigorous independent randomized trial and every major meta-analysis report none.
Evidence Supporting ERA
1. Simón 2020 — five-year multicenter RCT (ERA-RCT consortium) — published in Reproductive BioMedicine Online — PMID 32723696, this manufacturer-led trial is the largest supportive study and compares personalized transfer (pET), standard FET, and fresh transfer over five years across multiple countries.
A cumulative rate counts patients who achieved the outcome at least once during the study period, across all transfers from one retrieval — it is not the result of a single transfer.
| Outcome | pET (ERA-guided) | Standard FET | Fresh transfer | P value (pET vs FET) |
|---|---|---|---|---|
| Cumulative pregnancy rate | 93.6% | 79.7% | 80.7% | P=0.0005 |
| Pregnancy rate at first transfer | 72.5% | 54.3% | 58.5% | P=0.01 |
| Implantation rate at first transfer | 57.3% | 43.2% | 38.6% | P=0.03 |
| Live birth at first transfer | 56.2% | 42.4% | 45.7% | P=0.09 (not significant) |
| Cumulative live birth at 12 months | 71.2% | 55.4% | 48.9% | P=0.04 |
The positive results came from per-protocol analysis rather than the stricter intention-to-treat analysis, dropout reached 50% (versus 30% planned), and the live-birth difference at first transfer was not statistically significant (P=0.09) — details rarely emphasized in marketing.
2. Barbakadze 2024 RCT cited by Igenomix (Cureus). According to Igenomix’s official page, a randomized trial of 320 patients with recurrent implantation failure (RIF) found that ERA combined with PGT-A (preimplantation genetic testing for aneuploidy) nearly doubled live birth rates versus PGT-A alone. This study is the source of the claim that ERA is “the only receptivity test supported by an RCT.”
3. 2025 study cited by CNY Fertility. The US clinic CNY Fertility cites a 2025 study on its public education page: among women with multiple prior transfer failures, ERA-guided transfers produced a 48.2% live birth rate versus 26.1% with unguided standard transfers.
Evidence Against ERA
1) Doyle 2022 — JAMA randomized clinical trial (the strongest counter-evidence): This double-blind trial randomized 767 patients across 30 US centers — PMID 36472596. Everyone received an ERA test, but only the intervention group’s transfer timing followed the result; the control group used standard timing regardless.
- Live birth in the ERA-guided group: 58.5% (223/381)
- Live birth in the standard-timing group: 61.9% (239/386)
- Difference: −3.4% (95% CI −10.3% to 3.5%), P=0.38 — not statistically significant
ERA-guided transfer did not improve live birth rates. Notably, the trial excluded RIF and recurrent pregnancy loss patients — precisely the group ERA is most often recommended for — which is both a limitation and a warning that for average patients ERA likely just adds cost.
2. Arian 2023 systematic review and meta-analysis — Fertility & Sterility. An odds ratio (OR) above 1 means higher odds in the ERA group; below 1 means lower odds. The 95% confidence interval (CI) is the plausible range of the true effect — an interval crossing 1 means no clear difference.
Pooling 8 studies and 2,784 patients (831 ERA versus 1,953 controls):
- Live birth / ongoing pregnancy OR = 1.38 (95% CI 0.79–2.41, I²=83%, indicating high heterogeneity) — not significant
- Implantation, biochemical pregnancy, clinical pregnancy, and miscarriage rates showed no group differences
- Subgroup analyses by number of prior failed transfers also showed no difference
Current evidence does not show that ERA significantly improves pregnancy rates; whether it helps “remains unclear.”
3. Riestenberg 2021 — Fertility & Sterility. In a prospective cohort of patients undergoing their first single euploid frozen embryo transfer, routine ERA produced no live-birth improvement over standard timing. Routine ERA in unselected patients is not supported.
4. Cozzolino 2022 — Fertility & Sterility. A larger retrospective multicenter study found that patients who used ERA-guided personalized transfer after a failed attempt had lower cumulative and per-transfer live birth rates than those who did not. It is observational and may carry selection bias, but ERA is clearly not a guaranteed upgrade.
5. HFEA official rating: red. The UK regulator’s position anchors the skeptical camp:
“For most patients, moderate- or high-quality evidence shows that this add-on may reduce treatment effectiveness.” — UK Human Fertilisation and Embryology Authority, HFEA, red rating for endometrial receptivity testing, current as of August 2026
HFEA also raises two structural doubts: whether the test can accurately predict an individual’s window at all, and whether a woman’s window stays fixed from cycle to cycle. If the window drifts between cycles, a single test result loses its guiding value.
Evidence Summary: Should You Trust ERA?
| Question | What the evidence says |
|---|---|
| Useful for first-time or routine patients? | Probably not — the JAMA RCT, Arian meta-analysis, and Riestenberg cohort all show no benefit |
| Useful for recurrent implantation failure (RIF)? | Conflicting — some studies (including manufacturer trials) show benefit; the JAMA RCT, which excluded RIF, and several observational studies do not |
| Any risks? | The biopsy itself is low-risk (rare light bleeding or infection); the main risks are cost and a possible cycle delay |
| What does HFEA say? | Red rating: may reduce treatment effectiveness for most patients |
Who Should Consider an ERA Test?
The mainstream, non-manufacturer consensus is: not recommended routinely, but reasonable in specific situations. The strongest candidate profile is repeated failure despite good-quality embryos.
Groups that may benefit:
- Recurrent implantation failure (RIF): at least 2 failed transfers of good-quality (ideally PGT-A–normal) embryos, after uterine cavity, endocrine, and immune causes have been excluded — this is where ERA evidence concentrates;
- Failed transfer of a euploid embryo: when both embryo and chromosomes look “normal” yet implantation fails, lining timing is worth investigating;
- Normal lining thickness and pattern with repeated failure: when the doctor suspects a timing problem rather than a soil-quality problem.
Groups where routine ERA is not recommended:
- First-time transfers or fewer than 2 failures — the JAMA RCT clearly shows no benefit;
- Patients who have not completed a standard workup (adhesions, polyps, chronic endometritis, hydrosalpinx, immune factors) — basic testing comes before ERA;
- Budget-conscious patients — ERA is self-pay in the US at hundreds to over a thousand dollars, and most insurance plans do not cover it.
If you can afford it and have failed 2 or more transfers of good-quality embryos, one ERA works as a “mine-clearing” test: its value is excluding a timing problem, not guaranteeing success. A shifted-window result that changes your protocol may create a turning point; a “receptive” result at least redirects attention to other causes.
How Much Does an ERA Test Cost?
In the US, ERA is an IVF add-on and is almost never covered by insurance — expect to pay out of pocket. Prices vary by clinic, lab, and region:
- US market: a single ERA typically costs several hundred to over $1,000 as a biopsy-plus-analysis package, with some clinics charging more or offering bundled discounts;
- Repeat biopsy: roughly 10% of patients need a second test cycle, which adds another fee;
- Context: a full US IVF cycle typically runs $15,000–$25,000 including medications, a FET about $4,000–$6,000, and PGT-A about $3,000–$5,000 — ERA costs roughly one-fifth to one-third of a single FET.
Ask your clinic up front whether the quoted fee includes the biopsy procedure, the lab analysis, and a possible second biopsy, and whether any portion bills as a “diagnostic” service your insurance might partially cover.
FAQ
Q: Does the ERA test hurt?
The biopsy usually needs no anesthesia; most women feel brief lower-abdominal cramping or tugging for about 1–2 minutes. Light brown spotting for 1–2 days afterward is common, and the procedure is far less uncomfortable than egg retrieval.
Q: Is ERA the same as endometrial scratching?
No. ERA is a test — it samples tissue to analyze 248 genes and time your window.
Endometrial scratching is a treatment — it lightly injures the lining to trigger an immune response thought to aid implantation. HFEA rates scratching separately, with a “yellow” (insufficient evidence) rating.
Q: Does ERA add an extra cycle of time?
Yes. A full test cycle means medications to prepare the lining, the biopsy, about 1–2 weeks for lab results, and then transfer in the following cycle — roughly 1 extra menstrual cycle compared with going straight to transfer.
Q: My ERA said “receptive” but the transfer still failed — why?
ERA answers exactly 1 question: is the timing right? It cannot rule out embryo genetics, cavity problems such as chronic endometritis or adhesions, immune factors, or endocrine issues.
A receptive result excludes 1 cause, not all of them.
Q: What is the difference between ERA, EMMA, and ALICE?
They are 3 tests from the same lab (Igenomix): ERA checks receptivity timing, EMMA analyzes the endometrial microbiome, and ALICE screens for pathogenic bacteria linked to chronic endometritis. They can be combined as the “EndomeTRIO” package, but clinical evidence for EMMA and ALICE is even weaker than for ERA, and HFEA gives microbiome testing no positive rating.
Q: Is ERA available outside the US, and is it the same?
Many reproductive centers in China offer ERA — some partnered with Igenomix, others using domestic equivalents — with a process similar to the US. Interpretation standards and reference databases can differ, so complete the test and the transfer at the same center; prices are usually below the US range of several hundred to over $1,000, and still mostly self-pay.
Q: How many failed transfers justify an ERA?
There is no universal rule, but most guideline-level opinions suggest considering ERA only after 2 or more failed transfers of good-quality (ideally PGT-A–tested) embryos. For a first transfer, current evidence shows no benefit (Riestenberg 2021; Doyle 2022).
Should You Do an ERA Test? A 5-Point Decision Checklist
Work through these 5 steps before booking an ERA:
- Rule out other causes first: hysteroscopy for adhesions, polyps, and chronic endometritis, plus immune and thrombophilia workup and a male-factor review — all more foundational and cheaper than ERA.
- Count your failures: fewer than 2 failed good-quality transfers means the evidence does not justify ERA; 2 or more with euploid embryos puts it on the table.
- Ask your doctor 3 questions: what other causes remain, how an ERA result would change the plan, and what happens if the result is “receptive.” If the third question has no answer, ERA adds little to your case.
- Do the math: ERA plus a possible second biopsy plus one extra month — with a limited budget, PGT-A or hysteroscopy may deliver more value per dollar.
- Set expectations honestly: ERA is a diagnostic sweep that can exclude one cause, not a success guarantee.
To compare clinics for a next cycle, browse our global IVF clinic directory, or read our guides on recurrent implantation failure strategies, frozen embryo transfer, FET, and PGT genetic screening. Our advisors can also shortlist clinics by country and budget — contact us.
Medical disclaimer: This article is for educational purposes only and does not constitute medical advice. Whether to have an ERA test and when to transfer are decisions for you and your reproductive endocrinologist. Research data cited here is current as of August 2026, from peer-reviewed literature indexed on PubMed, HFEA official ratings, and manufacturer public materials.
This article was written by the ProIVF Medical Editorial Team and reviewed by the ProIVF Medical Advisory Board, drawing on Igenomix product materials, HFEA add-on ratings, public CDC/ASRM guidance, and peer-reviewed literature on PubMed. Igenomix and CNY Fertility information cited here comes from their public disclosures; ProIVF has no commercial relationship with any clinic or company mentioned.
Last updated: 2026-08-24
