Almost every IVF success chart is organised by age. That is because, for people using their own eggs, age is closely tied to how many eggs are available and how likely each one is to become a healthy embryo. The NHS lists age alongside the cause of infertility, BMI and lifestyle among the factors that affect IVF success (NHS, reviewed 2025). For a broader look at all of those factors, see what affects IVF success. Here we stay with age, and with how the numbers are built.
What one national register shows
The UK fertility regulator publishes yearly figures from its national register of every licensed treatment. Its latest report, published in 2026 and covering 2024 cycles, gives these figures for IVF using the patient's own eggs (HFEA, 2026):
Those are the two ends of the age range, plus the all-age average, as the report summarises them. Before using them, note what the report itself says about how they were calculated:
- The rate is per embryo transferred, combining fresh and frozen transfers.
- Age is the patient's age at egg collection, not at transfer.
- Cycles using embryo genetic testing (PGT) are excluded.
- Birth outcomes for 2024 are preliminary and not yet fully validated.
- The method changed from earlier reports, so the figures are not directly comparable with older years.
The same report shows the national average rising over time, from 20% in 2014 to 30% in 2024. So a figure you read in an older article may simply be out of date.
"Age" usually means the age of the eggs
Because the register groups results by age at egg collection, a frozen embryo keeps the age it was created at. Illustrative example: someone who froze embryos at 33 and transfers one at 37 would fall into the younger band for that embryo, because the egg was collected at 33. This is also why results with donor eggs are reported separately from own-egg results: the eggs come from someone else, usually younger, so the recipient's own age band does not describe them.
This has a practical meaning. If you are deciding between treatment now and treatment later, the clock that matters most is the one running on your eggs, which is why some people choose to freeze eggs or embryos first. Our guide on egg freezing and fertility preservation covers that option.
Three denominators, three different numbers
Most confusion about IVF statistics comes from the bottom half of the fraction. The same clinic, on the same patients, can produce very different-looking rates:
| Measured per… | What it counts | Why it looks the way it does |
|---|---|---|
| Embryo transferred | Births divided by embryos placed in the uterus | Leaves out cycles where no embryo reached transfer |
| Started cycle | Births divided by all cycles begun | Includes cancelled cycles and those with no embryos, so tends to be lower |
| Egg collection, cumulative | Births from all embryos from one collection, fresh and frozen | Captures the full value of a collection, but takes time to measure |
None of these is "the real" success rate. Each answers a different question. A per-embryo rate tells you what each transfer offers. A per-cycle rate tells you what starting treatment offers. A cumulative rate tells you what one round of stimulation is worth across all its embryos. When a clinic quotes a figure, ask which it is. Our guide to reading SART and HFEA success-rate data goes further into registry reports.
Per transfer versus cumulative: an illustration
Illustrative example, not real data: imagine one egg collection produces three embryos suitable to freeze. If each transfer has roughly a one-in-three chance, the per-transfer figure is about 33%. But across all three embryos, transferred one at a time, the chance that at least one leads to a birth is noticeably higher than 33%, because each transfer is another opportunity. Now imagine someone older whose collection produces only one embryo with a lower chance. Their per-transfer and cumulative figures are the same, because there is only one try. That is why age affects cumulative chance even more than per-transfer chance: it reduces both the number of embryos and the odds for each one.
Why rates fall with age
As age rises, two things tend to happen together. Fewer eggs are collected per cycle, and a smaller share of embryos have the right number of chromosomes. Fewer embryos, each with a lower chance, add up to the steep differences you see between the youngest and oldest bands. A healthy lifestyle helps in other ways but does not reverse these changes.
Age also shapes access in some systems. In England, the NHS says IVF is generally available to people aged 42 or under who meet the criteria, with up to three cycles for those 39 or under and one cycle for those aged 40 to 42 who have not had IVF before (NHS, reviewed 2025). Those rules reflect the age data, not a judgement about any individual.
How to use an age-band figure for yourself
An average describes a group, not you. Two people of the same age can have very different outlooks depending on their ovarian reserve, diagnosis and previous cycles. Use age-band numbers as a starting point, then ask your clinic to adjust:
- Start with the band. Find your age band in a national register's data, and note what it is measured per.
- Add your own markers. Your egg reserve tests and any previous response tell the clinic whether you are likely to sit above or below the band average.
- Ask about cumulative chance. For many people, the more useful question is the chance of a baby across all embryos from one or more collections, not per transfer.
- Ask the clinic for its own figures for patients of your age, with the denominator stated.
A note on figures from clinics abroad
Not every country has a national register, and clinics may report results in their own way. A clinic quoting high rates for older patients may be counting only those who reached transfer, or including donor-egg cycles. Ask whether figures are own-egg or donor-egg, per transfer or per cycle, and whether any patients were excluded.
What these numbers do not tell you
- They do not predict your result on any single attempt.
- They do not include cycles using embryo testing, in the UK register's case.
- They do not tell you whether a lower chance is still worth pursuing; that depends on your goals, finances and alternatives.
The Takeaway
Age-band success rates are real and steep, but they are averages with specific definitions. Know the age used, the denominator and the exclusions, then ask your clinic to place you within the band using your own results.
Frequently asked questions
Does my age at transfer or at egg collection matter more?
For own-egg IVF, national data are grouped by age at egg collection, because the egg's age is closely tied to embryo quality. The uterus still matters for pregnancy health, which is one reason clinics consider your current age too.
Why do different websites give different numbers for the same age?
They may use different years, countries, denominators or patient groups. Check the source, the year and what the figure is measured per before comparing.
Are success rates higher with frozen embryos?
The UK regulator does not report separate fresh and frozen birth rates in its 2024 summary and notes they are not directly comparable, partly because different patients have each type of transfer.
Is there an age after which IVF with my own eggs is not offered?
Funded treatment often has age limits, and many private clinics set their own. Policies vary by country and clinic, so ask directly.
Can I improve my odds beyond what my age suggests?
You cannot change the age of your eggs, but treating other factors such as weight, smoking and medical conditions can help you avoid adding further disadvantages. Ask your clinic which factors in your case are worth working on.