IVF success rates by age are the single most-asked question in a fertility consult, and the most-misquoted number on the internet. The reason: UK and US regulators report success differently, and a 35% headline can mean per embryo, per cycle, or cumulative over many transfers.
This post puts the two main data sources side by side, explains the denominators, and gives you age-banded numbers you can actually plan with. If you're still earlier in the process and deciding whether IVF is the right next step at all, when to consider IVF after TTC is the better starting point.
What "IVF Success Rate" Actually Measures
Three denominators dominate IVF reporting, and mixing them up is where most confusion starts.
The first is live birth per embryo transferred. This is the UK's HFEA headline metric and reflects the chance that any single embryo placed back into the uterus leads to a baby. The second is live birth per egg retrieval cycle, which counts a baby per stimulation regardless of how many transfers it took. The third is cumulative live birth rate, which sums all transfers (fresh and frozen) from a single stimulation, usually over 12 months. [src]
The CDC and SART, which report US data, lean on the cumulative-per-retrieval metric. [src] That single difference explains why US "success rates" often look higher than UK ones for the same age group.
A practical rule: live birth is the only number that matters for planning. Clinical pregnancy rates include miscarriages and biochemical losses and overstate your real chance of bringing a baby home.
UK Success Rates: HFEA UK IVF Data
The HFEA publishes annual live-birth-per-embryo-transferred figures for licensed UK clinics. The most recent data, pooled across all UK clinics, shows roughly the following pattern for fresh embryo transfers using patients' own eggs:
| Age band | Live birth per embryo transferred (HFEA, approx.) |
|---|---|
| Under 35 | ~32 to 35% |
| 35 to 37 | ~25 to 28% |
| 38 to 39 | ~18 to 21% |
| 40 to 42 | ~9 to 11% |
| 43 to 44 | ~4 to 5% |
| 44+ | ~1 to 3% |
Frozen embryo transfer rates have caught up with and in many UK clinics now exceed fresh transfer rates, driven by improved vitrification and freeze-all protocols. The average age of a UK patient on her first IVF cycle is now over 35, which pulls the pooled headline numbers down compared to a decade ago. [src]
HFEA's standard headline is per embryo transferred. If a clinic quotes you a UK success rate that's much higher than HFEA's age-banded average, ask which denominator they're using and over how many transfers.
US Success Rates: CDC SART IVF Data US
CDC and SART report cumulative live birth per intended egg retrieval, including all subsequent fresh and frozen transfers within about 12 months. This is a more generous denominator than HFEA's, which is why the headline US numbers look higher.
Approximate cumulative live birth rates per retrieval (own eggs) from recent SART national summary data:
| Age band | Cumulative live birth per retrieval (SART, approx.) |
|---|---|
| Under 35 | ~50 to 55% |
| 35 to 37 | ~38 to 42% |
| 38 to 40 | ~26 to 30% |
| 41 to 42 | ~13 to 17% |
| 43+ | ~4 to 7% |
"What is IVF success rate at 38" depends entirely on the denominator. Roughly 25 to 30% per fresh embryo transferred (HFEA-style), or cumulative around 30 to 35% per retrieval (SART-style). Both are correct; they're answering different questions. [src]
Why UK and US Numbers Look So Different
The headline gap isn't about clinical quality. It's about what you're counting.
HFEA per-embryo-transferred and SART per-retrieval cumulative are not the same denominator. If a US clinic stimulates, fertilises, freezes 4 blastocysts, and you eventually conceive on the third frozen transfer, SART counts one success per retrieval. HFEA would count three transfers, two failed and one successful, and the per-embryo rate would be 33%.
Clinic case-mix also differs. US patients often start IVF younger on average, use more elective single embryo transfer, and lean on freeze-all strategies. UK NHS-funded patients tend to be older at first cycle because of the typical referral pathway and age caps.
A 32% UK per-embryo number is not worse than a 50% US per-retrieval number. They count different things. Ask any clinic to give you both metrics for your age band before signing.
Live Birth Rate per Cycle by Age
Putting both sources together gives a more honest picture than either alone:
| Age band | UK per embryo transferred | US cumulative per retrieval |
|---|---|---|
| Under 35 | ~32 to 35% | ~50 to 55% |
| 35 to 37 | ~25 to 28% | ~38 to 42% |
| 38 to 40 | ~18 to 21% (38 to 39); ~9 to 11% (40 to 42 pool) | ~26 to 30% |
| 41 to 42 | ~9 to 11% | ~13 to 17% |
| 43+ | ~4% or lower | ~4 to 7% |
"How many IVF cycles on average to get pregnant" follows from these bands. Under 35, the majority of patients reach a cumulative live birth within 1 to 2 retrievals. Over 40 with own eggs, 3 or more retrievals may still under-deliver, which is when donor egg conversations begin. Donor egg cycles in both countries hold a live birth rate of roughly 45 to 55% per transfer regardless of the recipient's age, because egg age is the dominant driver of outcome, not uterine age. [src]
If you're weighing IUI first versus going straight to IVF, IUI vs IVF, which is right for you explains the decision logic. For practical readiness, how to prepare for your first IVF cycle is worth a read before stimulation starts.
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NHS vs US Pathway for Funding Those Cycles
UK / NHS: NHS-funded IVF varies by Integrated Care Board (ICB). Most ICBs fund 1 fresh cycle, with age caps usually at 40 (occasionally 42) and BMI thresholds typically 19 to 30. NICE NG257 sets the national framework, but local commissioning decides who actually qualifies. Private cycles in the UK typically run £5,000 to £7,000 plus medication. [src] See IVF cost in the UK, NHS vs private for a full breakdown.
US: Insurance coverage varies wildly by state and employer. About 20 US states have some IVF mandate, but the scope varies. Out-of-pocket cycles commonly run $15,000 to $25,000 including medications, with PGT-A and donor egg cycles costing significantly more. IVF cost in the US, what insurance covers explains coverage tiers.
What This Means for You
Use age-banded IVF success rates by age to plan how many cycles you can realistically attempt, not to predict cycle one in isolation. Ask your clinic for their own age-banded live birth per retrieval (not a pooled national figure, not a clinical pregnancy rate) before you sign, and ask whether their denominator matches HFEA or SART so you can compare like for like.
If you'd like help interpreting clinic-specific success rates against the national HFEA or SART benchmarks for your age band, an online consultation is a low-cost way to get a second clinical view before you commit.
Ready for a personalised fertility plan?
Book a one-to-one consultation. We'll review your history and map the next concrete step.
What is IVF success rate at 38?+
Approximately 18 to 21% live birth per fresh embryo transferred (HFEA UK headline), or approximately 26 to 30% cumulative live birth per egg retrieval (SART US headline). Both are correct; they count different things.
What is IVF success rate at 40?+
Roughly 9 to 11% per fresh embryo transferred (HFEA), or roughly 13 to 17% cumulative live birth per retrieval (SART). Donor egg cycles hold a much higher rate regardless of recipient age because egg quality drives the outcome.
How many IVF cycles on average to get pregnant?+
Under 35, the majority of patients reach a cumulative live birth within 1 to 2 retrievals. Over 40 using own eggs, 3 or more retrievals may still not deliver, which is when donor egg or alternative paths enter the conversation.
Are UK or US IVF success rates higher?+
The headlines look higher in the US because SART reports cumulative live birth per retrieval, while HFEA reports live birth per embryo transferred. When you match denominators, the gap narrows substantially. Neither system is "better"; they measure different things.
What does cumulative live birth rate mean?+
It's the chance of at least one live birth from all transfers (fresh and frozen) attached to a single egg retrieval, usually counted over 12 months. It's a more generous and arguably more useful number than per-transfer rates because it reflects what one stimulation actually delivers.
Does using donor eggs change success rates by age?+
Yes. Donor egg cycles maintain roughly 45 to 55% live birth per transfer regardless of the recipient's age, because egg quality (not uterine age) is the dominant driver of IVF outcome.
References
Citations referenced inline above link to their primary sources (NHS, NICE, CDC, ACOG, ASRM, peer-reviewed journals).
