Age is the most significant single variable in IVF success. This is not a generalisation — it is the result of a specific biological mechanism: the proportion of chromosomally normal (euploid) eggs declines markedly as women age, and chromosomal abnormality is the leading cause of IVF failure and early pregnancy loss.
This guide explains what the HFEA data shows for each age group, what those numbers mean in practice, and what factors beyond age can move your individual chances up or down.
How to Read IVF Success Rate Data
The HFEA (Human Fertilisation and Embryology Authority) publishes outcome data for all UK-licensed clinics. The headline figure is live birth rate per embryo transfer — the percentage of individual transfer procedures that result in a baby being born.
This is the right metric to focus on, but it has limitations:
- It does not account for cumulative outcomes across multiple cycles
- It includes all patients at that age, regardless of reserve, diagnosis, or number of previous cycles
- It does not distinguish between fresh and frozen transfers in aggregate figures
For your individual prognosis, cumulative live birth rate across 2–3 cycles is more informative than the per-transfer figure. Ask your consultant for their estimate of your cumulative chances.
For more on how to interpret clinic-reported figures, see HFEA success rates explained.
HFEA Data by Age Group (Own Eggs)
| Age | Live birth rate per embryo transfer | |---|---| | Under 35 | ~32–35% | | 35–37 | ~25–28% | | 38–39 | ~18–22% | | 40–42 | ~10–14% | | 43–44 | ~5–7% | | 45+ | ~2–3% |
These are approximate ranges based on HFEA aggregate data. Individual clinic rates vary; ask for the specific figures from your clinic for your age group.
Under 35: The Highest Baseline Success
Patients under 35 have the highest per-transfer success rates and the lowest aneuploidy rates — roughly 20–30% of embryos at this age are chromosomally abnormal, compared to over 80% at 43+.
Cumulative live birth rate over three cycles for patients under 35 with a typical profile is approximately 65–75%. This makes IVF highly effective for this age group — most patients who persist through multiple cycles achieve a successful outcome.
What can reduce chances below the average:
- Very low AMH or poor ovarian reserve (which affects egg number, though age still governs egg quality more than AMH does)
- Severe male factor infertility
- Uterine abnormalities
- Endometriosis (depending on severity)
35–37: Meaningful but Not Dramatic Decline
The decline in live birth rates between under-35 and 35–37 is real but modest. The aneuploidy rate per egg is approximately 30–40% in this group, and per-transfer live birth rates are still in the 25–28% range.
Over multiple cycles, cumulative success rates remain good — approximately 55–65% over three cycles for patients with adequate reserve.
This age group is where NHS eligibility policies vary most: some ICBs fund three cycles for patients up to 40; others begin restricting at 37–38. Check your local NHS eligibility criteria to understand what funding you may be entitled to.
38–39: Time Sensitivity Increases
At 38–39, the aneuploidy rate per egg reaches approximately 50–60%. This means more cycles are needed to produce a usable euploid embryo, and more transfers may fail because the transferred embryo was chromosomally unable to implant.
Per-transfer live birth rates of 18–22% are still meaningful — comparable to natural monthly fecundity rates in younger couples. But the reduced reserve that may be present, combined with higher aneuploidy, means that starting promptly and not delaying treatment is particularly important at this age.
For more on navigating IVF specifically at this age, see IVF at 38–39 in the UK.
40–42: Lower Per-Transfer Rates, but Success Remains Possible
The per-transfer live birth rate drops to approximately 10–14% at 40–42 with own eggs. Aneuploidy rates per egg are approximately 60–75%. This means the majority of embryos produced in a cycle will be chromosomally abnormal — but it does not mean that no euploid embryos will be produced.
Cumulative success across multiple cycles for patients in this group is approximately 25–40%. The question is whether the patient has adequate reserve and emotional/financial resilience to persist through multiple attempts.
PGT-A (genetic testing of embryos before transfer) is more commonly used at this age, as identifying euploid embryos becomes more valuable when the majority are aneuploid. See preimplantation genetic testing.
NHS funding for patients over 40 is limited. Many ICBs fund only one cycle for patients aged 40–42 who meet clinical criteria. Check your ICB's current policy.
For a guide specifically for patients over 40, see IVF after 40 in the UK.
43–44: Donor Eggs Become a Realistic Conversation
At 43–44, own-egg IVF success rates fall to approximately 5–7% per transfer. Most embryos at this age are aneuploid, and the probability of a euploid embryo in a typical cycle is low.
Some patients at this age have adequate reserve and pursue own-egg IVF — and some succeed. But the clinical reality is that many patients in this group who wish to have a child will have the best outcomes with donor eggs. Donor egg IVF at any age typically produces live birth rates of 40–50% per transfer, because the outcome tracks the age of the egg donor (typically under 35).
See donor egg IVF in the UK for a full guide on this pathway.
What Else Affects Your Chances (Beyond Age)?
Ovarian reserve (AMH): AMH predicts the number of eggs that can be retrieved, but does not directly predict their quality. An older patient with high AMH may produce more eggs, giving more chances to find a euploid embryo. A young patient with very low AMH may produce fewer eggs.
Cause of infertility: Couples with male factor infertility, endometriosis, or unexplained infertility may have different outcomes than the population averages. See unexplained infertility and endometriosis and IVF.
Clinic quality: The laboratory environment, embryo culture conditions, and embryologist expertise affect blastocyst development rate — which is the proportion of fertilised eggs that develop to usable embryos. See IVF laboratory quality.
Previous pregnancies: A previous live birth or previous positive IVF response generally improves prognosis. A history of recurrent pregnancy loss requires separate investigation.
Frequently Asked Questions
Q: I'm 36 with low AMH. Does that mean my chances are like a 42-year-old?
A: No. AMH predicts the number of eggs produced — not their quality. A 36-year-old with low AMH will likely have fewer eggs retrieved per cycle, but the chromosomal competence of each egg is still that of a 36-year-old. You may need more cycles to accumulate viable embryos, but your per-egg success rate is not equivalent to a 42-year-old.
Q: What is a realistic expectation across three IVF cycles at 39?
A: With adequate reserve and no major complicating factors, cumulative live birth rate across three cycles at 39 is approximately 40–55%. This is a population average — individual prognosis varies with reserve, embryology outcomes, and other factors.
Q: My clinic quoted me a higher success rate than the HFEA average. Should I believe it?
A: Possibly. Some clinics genuinely achieve above-average results due to laboratory quality. But also check whether the figure they are quoting uses the same denominator as HFEA data (per transfer, including all patients), and whether they have a policy of selecting lower-risk patients that inflates their numbers. See HFEA success rates explained.
Q: Is there a point at which IVF is too unlikely to be worth trying with own eggs?
A: This is ultimately a personal decision, not a clinical cutoff. At 45+ with own eggs, per-transfer success rates are approximately 2–3%, and many patients decide the cost and emotional investment is not worthwhile relative to donor egg alternatives. But some patients at 44–45 with good reserve do succeed. A frank prognosis conversation with your consultant — specific to your profile, not general statistics — is the right starting point.
This article is for information only. Success rates are population averages — your individual prognosis should be discussed with your fertility consultant.