Understanding HFEA success rates

The HFEA (Human Fertilisation and Embryology Authority) publishes success rate data for every licensed UK fertility clinic. The numbers are often misread. This guide explains what the figures mean, how to compare them fairly, and what to ask when a clinic quotes you a headline success rate.

Explainer · 5 min read · Reviewed 13 September 2026

In this explainer
  1. What the HFEA measures, and what it does not
  2. Why clinic comparison is harder than it looks
  3. How to find a clinic's HFEA data
  4. National benchmarks
  5. Sources

What the HFEA measures, and what it does not

The HFEA's Choose a Clinic pages show two measures: births per egg collection and births per embryo transferred. Its national reports use births per embryo transferred, the proportion of transfers that result in a baby. Neither is the same as 'per cycle started', which counts cycles that never reach transfer and so gives a lower figure.

Be wary of clinics that quote 'pregnancy rate' rather than 'birth rate'. Pregnancy rates, which include biochemical pregnancies and miscarriages, are higher and less useful for planning. Ask for the birth rate and how it was calculated.

The HFEA's national reports group patients by age at egg collection: 18 to 34, 35 to 37, 38 to 39, 40 to 42 and 43 to 44. Its Choose a Clinic pages currently show two groups, under 38 and 38 and over. The age of the egg at collection is what matters, not your age at transfer. If you are using frozen embryos created two years ago when you were 37, use the 35 to 37 figures.

Why clinic comparison is harder than it looks

Raw success rates are not a fair basis for comparison without context. The HFEA says small differences in rates are usually down to the different types of patients treated. Factors that move a clinic's numbers:

  • Patient mix: a clinic that treats more older patients or patients with a poorer prognosis will have lower headline rates even if it is good at what it does
  • Data lag: figures are published 18 months to two years after treatment. The HFEA's 2024 national data was published in June 2026, and clinic pages lag behind that.
  • Volume: clinics with lower patient numbers have more statistical noise in their rates, so a few percentage points either way is usually chance

The HFEA suggests looking at how patients and its inspectors rate a clinic, and at practical factors such as location, opening hours and counselling, alongside success rates.

Ask each clinic for its birth rate for your age group and treatment type, such as own eggs with donor sperm, and how many patients that figure is based on. A rate built on a small number of patients tells you little.

How to find a clinic's HFEA data

All licensed UK clinic data is publicly available at hfea.gov.uk/choose-a-fertility-clinic. You can search by location or clinic name.

When reviewing a clinic's page, look at:

  • Births per embryo transferred and births per egg collection, with the year the data covers
  • How the number compares with the national average, as marked on the page
  • Patient ratings and inspection ratings
  • Multiple birth rate

National benchmarks

In 2024 the UK average birth rate per embryo transferred was 30%: 38% for patients aged 18 to 34 and 8% at 43 to 44 (HFEA, preliminary figures).

These figures combine fresh and frozen transfers using the patient's own eggs, grouped by age at egg collection, and the HFEA says they are not directly comparable with its earlier reports. The report's charts also cover 35 to 37, 38 to 39 and 40 to 42; read them in the HFEA's Fertility treatment 2024: trends and figures report rather than relying on rounded figures here.

With donor eggs, birth rates are above 30% per embryo transferred at every recipient age (HFEA, 2019 data: 34% under 35, 31% at 45 to 50).

Sources

Last reviewed 13 September 2026. General information, not medical or financial advice. Your clinic and a regulated adviser can advise on your situation.

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