“Our success rate is 72%.” It is the first number on half the fertility clinic websites in the world, and standing alone it is close to meaningless. Not because clinics are all lying — some are excellent — but because without knowing what was counted, who was counted, and how many were counted, a percentage is decoration, not data. This matters double when comparing clinics abroad, because the reporting infrastructure you may be unconsciously relying on mostly does not exist outside a few countries.
The Reporting Systems That Do Exist
A handful of countries have mandatory, standardized, publicly searchable outcome reporting:
- United States: SART (the professional society registry) and the CDC’s federally mandated ART surveillance both publish clinic-level outcomes with standardized definitions, age bands, and cycle counts.
- United Kingdom: the HFEA licenses every clinic and publishes verified per-clinic data.
- Australia/New Zealand: ANZARD collects comprehensive cycle-level data.
Much of the rest of the world — including most popular IVF-abroad destinations — has either voluntary registries, aggregate national reporting without clinic-level breakdowns, or no public registry at all. ESHRE compiles European data, but participation and granularity vary by country. In Latin America, the REDLARA network aggregates regional data from member clinics, which is valuable context but is not a searchable per-clinic report card with standardized denominators.
The Denominator Games
Here is how the same clinic performance produces very different marketing numbers:
- Pregnancy rate vs live birth rate. Positive tests and early pregnancies are meaningfully more common than live births. A clinic advertising “pregnancy rate” is quoting the flattering intermediate outcome. The number you care about is live birth.
- Per transfer vs per cycle started. “Per transfer” excludes everyone whose cycle was cancelled, whose retrieval produced no viable embryos, or whose embryos didn’t survive to transfer — filtering out the hardest cases before the math starts. Per-cycle-started is the honest denominator for predicting your odds from day one; per-transfer is still useful, but only labeled as what it is.
- Blended ages. A single all-ages number is dominated by the clinic’s youngest patients. Outcomes differ dramatically by age band; a number without an age band attached tells you about the clinic’s patient mix, not its quality.
- Donor eggs mixed with own eggs. Donor-egg cycles succeed at high rates regardless of the recipient’s age. A clinic doing heavy donor volume can post a spectacular blended number while telling you nothing about own-egg outcomes for someone like you.
- Cumulative vs single-transfer. “90% success” sometimes means cumulative live birth across three or more transfers from one retrieval — a legitimate and even useful statistic, but not comparable to a single-transfer rate.
- The invisible cycle count. A 65% rate built on 40 cycles is statistical noise. The percentage means little without the raw count behind it.
How to Force an Apples-to-Apples Comparison
You cannot fix the missing registries, but you can make every clinic answer the same question. Send each clinic you are comparing this exact request, in writing:
Then read the responses like this:
- A clinic that answers specifically, with counts, in writing — whatever the numbers say — has just demonstrated the data discipline you want in an embryology lab. Honest mid-range numbers with real denominators beat spectacular numbers with none.
- A clinic that responds with the website marketing number, changes the subject to testimonials, or says the data “isn’t broken down that way” has also answered your question. A lab that doesn’t track its outcomes by age and cycle type either has weak quality systems or does not want you to see them. Either way: keep moving.
Signals Beyond the Percentage
Because self-reported numbers abroad are unverifiable, triangulate with structural signals that are harder to fake: annual cycle volume (embryology quality correlates with volume), lab accreditation and embryologist staffing ratios, whether the clinic participates in a national or regional registry (REDLARA membership in Latin America is a positive signal of at least submitting to outside data collection), and how the clinic talks about failure — a clinic that openly discusses its cancellation policy and what happens after an unsuccessful transfer is run by adults. Our virtual consultation checklist covers the full question set.