- You've seen clinic success rates and aren't sure what they're actually measuring
- You're comparing clinics or countries using their published percentages
- You want to understand why a number can look very different depending on how it was calculated
- You're deciding whether success-rate data should influence your country choice
Why published success rates mislead
Of 95 clinics and agencies audited across 8 countries:
- 34 publish specific donor egg rates
- 37 publish partial or vague information
- 24 publish nothing at all
Even among those that publish something, the numbers aren't comparable. They differ by metric, denominator, timeframe, and verification standard.
Three structural problems explain most of the confusion.
- If a clinic shows only one high percentage, treat it as incomplete until you know the metric, denominator, year, and whether the figure is self-reported or verified.
- If the rate is cumulative, don't compare it with a single-transfer rate. They're measuring different things across different numbers of attempts.
- If the rate is per embryo transfer, ask what happened to patients whose cycle never reached transfer. Those cycles are excluded from the denominator.
- If the rate is per cycle started, that's a more complete picture, since cancelled or failed cycles before transfer are included.
- If the clinic does not state the data year, treat the figure as weak evidence. Reporting cycles often run 2 to 3 years behind.
- If a clinic cannot explain its number clearly, including what it counts and how the figure was checked, treat it as weak decision evidence.
What exactly is being measured
Five different metrics are used across the industry, ordered below from least to most decision-useful.
Clinics choose which stage to advertise. The earlier the stage, the higher the number. Live birth rate is the most decision-useful outcome when it's available, but even that figure needs a denominator to be meaningful.
Why the denominator changes the story
Even when two clinics both quote "live birth rate," they may be measuring from different starting points.
A "per transfer" rate and a "per cycle started" rate are not interchangeable. The gap between them varies and depends on clinic practice, but treating the two as equivalent will give you a misleading comparison. Always check which denominator a clinic is using before drawing any conclusions.
A clinic that routinely cancels cycles before transfer, if embryo quality looks poor, will show a higher "per transfer" rate than a clinic that carries every cycle through to transfer. The patients who were cancelled don't disappear. They just aren't in the denominator.
Why cumulative rates look so high
Some clinics advertise 80 to 98% success rates. These almost always refer to cumulative rates across multiple transfers, not a single attempt.
- The real potential of a batch of embryos across multiple attempts
- A meaningful long-term success picture for patients planning repeat cycles
- What happens on the first transfer
- How they compare with per-transfer or per-cycle-started rates. They don't map directly.
Before accepting a cumulative figure, ask these questions.
Directional expectations for a single frozen donor egg transfer, based on national-level donor egg data. These are editorial ranges, not clinic-level guarantees.1
- 45–60% clinical pregnancy rate per transfer
- 35–50% live birth rate per transfer (lower than clinical pregnancy rate)
- 80–98% cumulative rates after 2 to 3 cycles, but this requires multiple attempts and additional cost
Which countries have more trustworthy public data
A success rate is only as trustworthy as the system behind it. In some countries, outcomes are tracked by a public authority and independently verified. In others, the figures on a clinic's website are largely self-reported.
| Country | Public data quality | What is usually published | Strongest public source | Main limitation |
|---|---|---|---|---|
| UK | High | Government-verified live birth data | HFEA (mandatory) | Donor eggs excluded from HFEA per-clinic comparison tool |
| Spain | High | National aggregate data via SEF (2023) | SEF national aggregate | No standardized clinic-level public data |
| Portugal | Moderate | National aggregate data via CNPMA (2022) | CNPMA national aggregate | Almost no clinics publish specific donor egg rates independently |
| Denmark | Moderate | National aggregate via DFS (2024) | DFS national data | Clinic-level comparison limited and inconsistent |
| Czech Republic | Moderate | Some clinic figures; no public national registry | Self-reported clinic figures | Inconsistent definitions; registry not accessible for patients |
| Greece | Moderate | Some clinic figures; ESHRE voluntary benchmark (older data) | ESHRE voluntary data | No national donor egg registry; figures mainly self-reported |
| North Cyprus | Low | Clinic websites only | None | No national registry; rates are self-reported and unverified |
| South Africa | Low | Sparse clinic publication; registry data is outdated | None current | No reliable public benchmark |
These tiers rank countries by how trustworthy and comparable their published data is, not by success rate.
A country ranked as High transparency doesn't guarantee better outcomes. A low-transparency environment doesn't mean worse clinics.
Strong public data infrastructure. National aggregate donor egg data is available. Meaningful benchmarks exist for context.
National aggregate data exists. Clinic-level data is limited or inconsistent. Useful as a national benchmark, not for direct clinic comparison.
Some clinics publish rates, but no reliable national donor egg registry is accessible for patient comparison. Many figures are self-reported.
No national registry. Rates are self-reported and unverified. Treat any published figure as a starting question, not a benchmark.
A note on the UK. It has the strongest regulatory framework and the most standardized reporting environment of any covered destination, with government-verified live birth data through HFEA. However, HFEA excludes donor eggs from the per-clinic comparison tool in the way patients often expect, so it's not a straightforward clinic-by-clinic shortcut for donor egg treatment specifically.
What success rates should and shouldn't change in your decision
Success rates are more useful for judging transparency than for choosing a country.
- Whether a clinic explains its data clearly and honestly
- How to identify transparent versus weakly substantiated claims
- Whether a clinic's figure is verified externally or self-reported
- What directional range is reasonable for national-level donor egg outcomes
- Whether you'll be accepted for treatment at that clinic
- How long donor matching will take for your requirements
- What the total cost will be including travel and medication
- How many usable embryos the cycle is likely to produce
Don't choose a country based mainly on published success rates. Choose first by eligibility, donor type, age limits, cost, travel burden, and overall shortlist fit. Only after narrowing to realistic destinations should success-rate questions be used to assess transparency and ask smarter questions of clinics.
Questions to ask a clinic before trusting a figure
What you gain and give up when you stop chasing headline rates
Use success rates late, not early. First narrow by eligibility, donor type, age limits, cost, and practical shortlist fit. Then use success-rate questions to assess how transparently a clinic explains its data.
- Success rates are per embryo transfer, not per cycle started. Individual results vary.
Common questions
A 70% live birth rate per transfer would sit above what national-level donor egg benchmarks usually suggest. In many cases, a clinic quoting 70% is referring to a different metric, such as clinical pregnancy rate or a cumulative figure across multiple transfers. Stricter patient selection can also lift published figures. Ask specifically for live birth rate per cycle started, what year it covers, and whether the figure has been externally verified.
Not meaningfully in most cases. Definitions, patient selection, and reporting standards differ too much for clean comparison. National aggregate data in Spain, Portugal, and Denmark can give useful context, but not a reliable clinic-by-clinic country ranking.
Several reasons, not all of them positive. Higher rates often reflect stricter patient selection: clinics that restrict intake to less complex cases will post better numbers. They may also reflect an earlier metric such as clinical pregnancy rate rather than live birth rate, or a cumulative figure rather than a per-transfer rate. Clinics that cancel cycles before transfer, if embryo quality looks poor, will also show a higher per-transfer rate, because the cancelled cycles don't enter the denominator. A higher published number can mean better clinical performance, but it can equally mean stricter intake or selective measurement.
They shouldn't drive the initial choice. Country decisions are better made on eligibility (age limits, single-woman access, donor type laws), practical fit (cost, travel, timeline), and shortlist logic. Success-rate data becomes more useful once you've narrowed to two or three realistic destinations. At that point, use it to assess transparency: a clinic that can explain its denominator, cite its data source, and break down what's included is worth more confidence than one that quotes a headline percentage without context.
Ask for live birth rate specifically, not clinical pregnancy rate or beta-hCG rate. Ask whether it's per embryo transfer or per cycle started, since the two are not directly comparable. Ask what year the data is from, whether it includes all donor egg patients or only a selected group, and whether the figure is self-reported or verified by an external body or national registry. A clinic that can answer all of these clearly is in a different category from one that can only give you a single percentage.