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Methodology and data source

This site does one thing: it structures the official data of the Spanish national registry so that any patient can consult and compare it rigorously. These are the rules.

The source: the official registry

All activity and results data come from the Spanish National ART Activity Registry (Registro Nacional de Actividad en Reproducción Humana Asistida), owned by the Ministry of Health (National Commission on Assisted Human Reproduction) and operated under contract by the Spanish Fertility Society (SEF). Three things make it unique:

  • Mandatory reporting: every centre must report its activity. It is the census, not a sample.
  • Independent auditing: more than 10% of centres are monitored each year by an external firm. The registry received Spain’s National Healthcare System Quality Award (2010).
  • Declared purpose: “to provide patients with information that reliably reflects the activity and results of the centres”. Exactly what this site does.

The registry requires citing the source under the exact name “Registro Nacional de Actividad 2023-Registro SEF”, and we do so on every data block. We currently publish the complete census (338 centres active in 2023) and the detailed results profile of 329 clinics; the rest will follow.

How to read the success rates

  • The interval is the figure. The registry publishes every rate as an interval (e.g. “27.4 – 68.2%”). A wide interval usually means few cycles; a narrow one, more activity. We never reduce it to a single number.
  • Compare within your age group and your technique. The probability with own oocytes at 34 and at 41 are different worlds; egg donation is a different technique with different results.
  • Beware of case-mix. Clinics treat different patients: one that accepts difficult cases can have lower rates and still be excellent. Most centres are within the national average.
  • A singleton pregnancy is the goal. The SEF recommends transferring 1 or 2 embryos; a singleton pregnancy is the best clinical outcome. A centre with many multiple pregnancies deserves a question.

Official registry guides (in Spanish):how to interpret a centre’s data,glossary and frequently asked questions (PDF).

Our product rules

  1. Exact attribution of the source on every figure, with the capture date and data year visible.
  2. Data always stratified by technique and age group — never a ranking or a “top clinics” list.
  3. The official data is never altered, and it will never be possible to pay to change it.
  4. What the registry does not publish, we do not show: no figure on this site is our own estimate.
  5. No medical advice: information to decide together with your medical team, not instead of it.

Frequently asked questions

Where does the data on this site come from?
From the Spanish National ART Activity Registry (Registro Nacional de Actividad en Reproducción Humana Asistida), owned by the Ministry of Health (CNRHA) and operated under contract by the Spanish Fertility Society (SEF). Reporting is mandatory for all centres, and more than 10% are audited each year by an independent firm. We cite the source on every figure under the exact name the registry requires: “Registro Nacional de Actividad 2023-Registro SEF”.
Why are success rates shown as intervals instead of an exact figure?
Because that is how the registry publishes them: a statistical interval reflects the uncertainty of the result (a clinic with few cycles has a wider interval). Publishing a single figure would give a false sense of precision. We reproduce the official intervals without altering them.
Why don’t you rank clinics?
Because comparing raw rates between centres is scientifically unsound: each clinic treats patients with different ages, causes of infertility and prognoses (the “case-mix”), and the SEF itself warns about this. Most clinics have results within the national average. That is why we show the data stratified by technique and age group, never an ordered list of “best clinics”.
Which year is the data from?
From 2023 activity, the most recent published: the registry publishes with a lag of about two years. The capture date appears at the foot of every data block.
Does this site provide medical advice?
No. We structure and cite data from the official registry to help you inform yourself; treatment decisions should always be made with healthcare professionals.
Do clinics pay to be listed?
No. The directory is the complete census of the official registry: every centre with recorded activity appears, and the official data is never altered — nor can anyone pay to change it.