IVF Success Rates in Istanbul: How to Read the Numbers
Key evidence: HFEA: understanding clinic statistics ESHRE: European registry data for 2020
When comparing IVF clinics in Istanbul, start with what each percentage counts: a positive test, a pregnancy seen on ultrasound, or a live birth. Then check whether it is calculated per treatment started, egg collection or transfer. These figures answer different questions; none is a personal forecast.
Table of contents
- What does a success rate measure?
- Why can two percentages differ?
- Which age matters?
- Do treatment add-ons change the picture?
- Frequently asked questions
- From a clinic average to your own situation
What does a success rate measure?
The word “success” needs a definition. A positive blood pregnancy test (β-hCG) does not establish the pregnancy’s location or whether it will continue. Clinical pregnancy is usually documented by ultrasound; a heartbeat is a separate finding. A live birth does not, by itself, describe a baby’s health or whether the birth was at term. These distinctions follow the international fertility-care glossary.
The denominator is what the result is divided by. For example:
| Rate reported | What to check |
|---|---|
| Per treatment cycle started | Are cycles cancelled before egg collection included? |
| Per egg collection | Are patients with no embryo available for transfer included? |
| Per transfer | This includes only cycles that reached transfer. Is the unit a transfer procedure or an individual embryo? |
| Cumulative live birth | Which fresh and frozen transfers are included, from how many collections, and over what follow-up period? |
The cumulative live-birth delivery rate per egg collection follows the fresh and frozen transfers from that collection until a delivery with at least one live-born baby occurs or all embryos have been used. A twin delivery counts once. This is the measure defined in the international glossary.
It is not the sum of the percentages for each transfer. For example, two transfers each reported as having a 30% chance do not give a 60% cumulative chance. Check whether the published figure covers one collection or several, how long patients were followed and whether all outcomes were known.
Before comparing figures, ask for the reporting dates, age groups, treatment type, sample size and missing outcomes. The HFEA’s guide to comparing clinics also explains uncertainty ranges: small differences do not necessarily mean that one clinic performs better.
Why can two percentages differ?
A rate can change because the calculation changes. In a “freeze-all” cycle, embryos are frozen for later transfer. Excluding these collections from a fresh-treatment calculation changes the denominator; freezing itself does not automatically change every rate’s definition.
The ESHRE registry report for 2020, published in 2025, covered 1,440 clinics in 41 countries. Clinical pregnancy per egg collection in conventional IVF (excluding ICSI) was 22.1%, or 26.4% excluding freeze-all cycles; after frozen embryo treatment it was 34.9% per thawing cycle. These are different groups and denominators. Reporting completeness varied between countries.
Those European averages are neither Istanbul clinic results nor evidence that freezing causes better outcomes. A comparison also needs similar patient groups and the same outcome. A pregnancy rate among patients who reached transfer cannot be substituted for a live-birth estimate before treatment begins.
Which age matters?
For embryos created with a patient’s own eggs, check the age at egg collection, including when the transfer happens years later. The HFEA’s 2024 UK report, published in June 2026, uses this distinction for frozen transfers. Its 2024 birth data are preliminary and unvalidated.
Age alone is not enough for an individual estimate. Diagnosis, ovarian reserve, sperm findings and previous embryo development also need review. An international statistic must specify whose eggs were used; different egg sources should not be pooled as though the patients had the same prognosis.
Do treatment add-ons change the picture?
A higher percentage after an extra test may reflect which embryos reached transfer. It does not automatically mean that more patients starting treatment will have a baby.
Time-lapse imaging records embryo development inside an incubator. The HFEA assessment of time-lapse finds no improvement in the chance of having a baby for most patients, whether images are assessed manually or by algorithms.
PGT-A checks chromosome numbers in sampled embryo cells. The HFEA assessment of PGT-A distinguishes fewer miscarriages from a greater chance of having a baby. It rates the latter red for most patients: selection may reduce available embryos and treatment effectiveness. A shorter time to pregnancy should not be promised.
Frequently asked questions
How many IVF attempts might be needed?
There is no fixed number. First clarify what “attempt” means: starting stimulation, collecting eggs or transferring an embryo. Several transfers may come from one collection. An estimate should specify the treatment being considered and how long outcomes were followed.
Does one unsuccessful transfer mean that future transfers will fail?
No. One unsuccessful transfer does not by itself establish recurrent implantation failure. The next assessment depends on the treatment history; it does not automatically require a broad panel of additional tests. The ESHRE recommendations on recurrent implantation failure do not recommend routine uterine or vaginal microbiome profiling.
Our guide to a second opinion after unsuccessful IVF explains how to prepare previous records for review.
Can fresh and frozen transfer rates be compared directly?
Only with careful attention to patient groups, embryo stage, egg-collection age and the calculation used. A higher frozen-transfer rate alone does not show that freezing improved the outcome. Frozen embryos are not necessarily all blastocysts.
Can a clinic's average tell me my own chance of a live birth?
No. It describes a group. Ask how closely that group resembles your situation, what outcome was counted and which cycles were excluded. Even a well-matched estimate remains uncertain.
From a clinic average to your own situation
Bring the published figure and its definition to the consultation, alongside previous treatment and embryology reports. They help distinguish what is known from what still needs assessment. The step-by-step IVF guide explains where collection and transfer fit in the treatment process.
Medical information
Evidence and wording checked on 16 September 2026: outcome definitions, registry denominators and treatment add-ons.
This page provides general information. It does not replace an individual assessment by a fertility specialist. Physician profile: Dr. Senai Aksoy.
Sources
Sources checked on 16 September 2026. Official document titles are retained below.
- Zegers-Hochschild F, Dyer S, Adamson GD, et al. The International Glossary on Infertility and Fertility Care, 2025. Fertility and Sterility. 2026;126(1):127–149. DOI: 10.1016/j.fertnstert.2026.02.022.
- Human Fertilisation and Embryology Authority (HFEA). Choose a fertility clinic.
- European IVF Monitoring Consortium (EIM) for ESHRE; Smeenk J et al. ART in Europe, 2020: results generated from European registries by ESHRE. Human Reproduction. 2025;40(11):2038–2055. DOI: 10.1093/humrep/deaf179.
- HFEA. Fertility treatment 2024: trends and figures. June 2026.
- HFEA. Time-lapse imaging and incubation.
- HFEA. Pre-implantation genetic testing for aneuploidy (PGT-A).
- ESHRE Working Group on Recurrent Implantation Failure; Cimadomo D et al. ESHRE good practice recommendations on recurrent implantation failure. Human Reproduction Open. 2023;2023(3):hoad023. DOI: 10.1093/hropen/hoad023.
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