IVF Success Rates by Age: How to Read the HFEA Numbers

The honest picture, with numbers

The HFEA is the UK regulator and it publishes the national figures, which is why every number on this page carries the cohort year it came from. Clinic-published success rates are not equivalent: they describe a selected group of patients that the clinic itself chose to treat, so they cannot be compared with each other or with the national figures.

2024 treatment cohort, using patients' own eggs across fresh and frozen transfers: the average IVF birth rate per embryo transferred was 30%. Patients aged 18 to 34 had the highest rate at 38%; patients aged 43 to 44 the lowest at 8%. The average age at the start of IVF was 34.8.

2023 treatment cohort, which separates fresh from frozen. Fresh transfers with the patient's own eggs: pregnancy rate 31% per embryo transferred overall, 41% at 18 to 34, 34% at 35 to 37, 25% at 38 to 39 and 9% at 43 to 44; birth rate 25% overall, 35% at 18 to 34 and 5% at 43 to 44. Frozen transfers: pregnancy rate 39% and birth rate 33% per embryo transferred.

One caveat governs all of it. The HFEA states that its recent birth figures are preliminary rather than validated and are likely to be underestimates, and it suggests using pregnancy rates as the better indicator of recent progress. Anyone quoting a single UK IVF success rate to two decimal places is not reading the source.

Per embryo transferred is not per cycle

This is the most consequential misreading of HFEA data. The headline figures are expressed per embryo transferred. A full cycle, as NG257 defines it, is one episode of ovarian stimulation plus the transfer of any resulting fresh and frozen embryos. If a stimulation produces three transferable embryos, you get three goes at that percentage, not one.

So the number that answers your real question — what is the chance this round of treatment ends with a baby — is higher than any single row in the table, and it depends on how many embryos your stimulation produced. That is the figure to ask your clinic for: cumulative live birth per stimulation cycle, for your age band.

Fresh and frozen are not comparable

Frozen transfer rates look better than fresh ones in the HFEA data, and the regulator explains why they should not be read as a like-for-like comparison: patients having frozen transfers are more likely to have had good quality embryos suitable for freezing in the first place. You are comparing a filtered population with an unfiltered one.

A related point that spares a lot of anxiety: for frozen transfers, pregnancy and birth rates are largely related to your age at egg collection rather than your age at transfer.

What else moves the number

Age is the dominant variable but not the only one. In the 2022 to 2024 data, the HFEA records an average birth rate per embryo transferred for patients aged 18 to 37 of 30% for Asian patients and 30% for Black patients, against 36% for White patients and 35% for patients from a Mixed ethnic background. The regulator states plainly that the reasons are not explained by its data and may relate to age at treatment, reproductive and general health conditions, and social and economic factors. It is a documented inequality, not a biological given.

Family type also shows differences in the same age band: 42% for patients in female same-sex couples, 39% for single patients and 35% for patients in opposite-sex couples, which largely reflects why each group is having treatment.

How to compare clinics without being misled

The HFEA runs Choose a Fertility Clinic, which publishes every licensed UK clinic's data alongside inspection ratings and patient ratings. Use it rather than clinic marketing, for three reasons.

First, a clinic's overall rate is dominated by whichever age group it treats most. A clinic that treats mostly under-35s will always look better than one that specialises in complex cases.

Second, patient selection is invisible in a headline figure. Declining to treat people with a poor prognosis raises a published rate without improving anyone's care.

Third, the HFEA's own list of questions to ask includes exactly the right one: how many patients at your clinic have had this treatment in the last two years, and how many of them have become pregnant or had a baby. Ask it for your age band and your indication.

Two further quality signals sit outside the success rate. The HFEA sets clinics a target that fewer than 10% of their IVF births should be multiples, and reports that around 90% of clinics met the 10% target in the 2023 cohort. And add-on use is a signal in itself: the HFEA maintains a rated list on which no add-on is currently rated green for improving the chance of a baby for most patients, so heavy promotion of extras tells you something about a clinic.

What the national picture says about waiting

The HFEA reports that most patients — 83% in the 2023 cohort — started IVF under 40, and notes that because birth rates decline with age and NHS funding is less common over 40, earlier treatment can increase the chance of success. NG257's access criteria are built on the same logic: 3 full cycles recommended under 40, 1 full cycle at 40 or 41, and no offer of IVF from the 42nd birthday. Time spent waiting for investigation is time subtracted from eligibility later.

What to do next

1. Ask for cumulative live birth per stimulation cycle for your age band, not the clinic's overall rate.
2. Check the clinic on the HFEA's Choose a Fertility Clinic service, including inspection outcomes and multiple birth rate.
3. Ask how many patients in your age band and with your diagnosis the clinic treated in the last two years, and what happened to them.
4. Ignore any percentage quoted without a cohort year and a denominator.
5. Ask what proportion of the clinic's patients use add-ons, and which ones.
6. Ask what would change the plan after an unsuccessful cycle before you start the first one.

When to seek help

NG257 recommends assessment of both partners after 1 year of unprotected vaginal intercourse, referral at first presentation from age 36, and immediate referral where either partner has a known or suspected clinical cause of infertility. Given how steeply the HFEA's by-age figures fall after 40, and that NICE recommends no IVF offer from the 42nd birthday, the practical advice is unglamorous: start the investigation conversation earlier than feels necessary, because the calendar is the one variable nobody can improve later.