What IVF success rates really mean, and how to read a clinic's numbers

“Success rate” is the most quoted and least standardised number in fertility care. Two clinics can both advertise 60% and mean completely different things. Here is what the current evidence says a realistic result looks like, and the four questions that make any clinic’s figure interpretable.

A modern benchmark

At ESHRE’s July meeting, Dr Dean Morbeck presented follow-up on 18,396 women who began IVF at seven Australian clinics between 2012 and 2021, tracked through to the end of 2023.

Across three cycles, 68.2% had a live birth (per-protocol), or 58.7% counting everyone who started regardless of whether they completed treatment. By age:

Age	Cumulative live birth rate over three cycles
Under 35	84.5%
35–37	74.4%
38–40	57.7%
41–42	30.1%

Two details matter more than the headline. First, this was achieved with single embryo transfer in 95.3% of transfers, and the multiple birth rate was just 2.9%. Transferring one embryo at a time did not cost these patients results — and it avoided the serious risks that come with twin pregnancies. Second, genetic testing of embryos (PGT-A) was used in about 25% of patients — a reminder that testing is a clinical decision made case by case, not a box everyone ticks. Whether it fits your situation is a question for your specialist.

Caveats: this was a conference abstract, retrospective, and it excluded patients using donor eggs or frozen eggs, so it does not describe those pathways. Results from one Australian clinic network will not transfer directly to any other lab.

The independently audited version

The UK’s regulator publishes the most rigorously audited national dataset available. Its 2024 figures put the average birth rate at 30% per embryo transferred, from 38% at ages 18–34 down to 8% at 43–44.

Notice these two credible sources appear to disagree — 68% versus 30% — but they are measuring different things. One counts babies after up to three cycles. The other counts babies per single embryo transferred. Both are correct. This is precisely why the denominator matters more than the percentage.

The four questions

Whenever a clinic gives you a number, ask:

1. Per what? Per cycle started, per egg retrieval, or per embryo transfer? These fall in that order, and the gap is large. A clinic that quotes per-transfer excludes everyone whose cycle was cancelled or who produced no viable embryo — which flatters the figure without lying.

2. Measuring what? Positive pregnancy test, clinical pregnancy (a heartbeat on ultrasound), or live birth? Only the last one is a baby. Roughly speaking, each step down loses a meaningful share.

3. For whom? Broken down by age band, and separately for own eggs versus donor eggs. A clinic with many donor-egg patients will post a high overall average that says nothing about your odds with your own eggs at 39.

4. Over how many attempts? A cumulative rate across three cycles is a much better planning number than a per-cycle rate, because it reflects how treatment actually works.

What to do with the answers

If a clinic answers all four clearly, that is itself a quality signal — it means they track their outcomes and are willing to be measured. If you get a single large number with no denominator, you are reading marketing.

Two more things worth knowing. Published national averages should be your sanity check: a clinic claiming results far above the audited national figures for your age group is making an extraordinary claim, and extraordinary claims need explaining. And be cautious when a very high success rate comes packaged with double embryo transfer — twin pregnancies carry substantially higher risks of prematurity and complications for both parent and babies, and a higher “pregnancy rate” bought that way is not a better outcome.

The UK data also flagged something clinics rarely discuss: birth rates were 30% for Black and Asian patients aged 18–37 versus 36% for White patients. If you belong to a group where outcomes differ, asking a clinic what they see in their own data is a fair question.

Realistic numbers are not discouraging. They are what lets you plan how many attempts to budget for — which, as the economics of this treatment make clear, is usually the decision that matters most.

If you want to see how a treatment cycle is structured step by step, read through the patient journey.