When you compare IVF clinics in Thailand, you will likely see success rate figures. These numbers can be helpful, but they are often reported in different ways. A clinic may report a clinical pregnancy rate, a live birth rate, or a rate per embryo transfer. Without knowing the definition, it is hard to compare one clinic’s number with another’s. This guide explains common metrics, the factors that influence them, and the questions you can ask to understand what a number really means for you.
At a glance
- Success rates are not a personal prediction; they describe a group of patients.
- Live birth rate is generally more meaningful than clinical pregnancy rate, but definitions vary.
- Age, embryo stage, and whether PGT was used can change the denominator.
- Ask how many patients were included and over what time period.
- Request written confirmation of definitions and inclusions before comparing clinics.
Why success rate numbers can be misleading
IVF success rates are statistics. They summarise the experience of a group of patients, not a guarantee for any one person. A clinic might report a high number because it treats a younger patient group, transfers more embryos, or counts early positive pregnancy tests rather than live births. Another clinic might report a lower number because it treats older patients or includes more challenging cases. Without context, a single percentage tells you very little.
Also, success rates change over time. A figure from 2023 may not reflect a clinic’s current results. When you see a number, ask when the data was collected and whether it has been audited.
Common IVF success metrics explained
Clinics use different terms. Here are the ones you are most likely to encounter.
- Clinical pregnancy rate: The percentage of cycles that result in a pregnancy confirmed by ultrasound (usually a gestational sac). This does not mean a baby will be born.
- Live birth rate: The percentage of cycles that result in at least one live birth. This is often considered the most meaningful outcome, but it can be reported per cycle, per embryo transfer, or per patient.
- Ongoing pregnancy rate: The percentage of cycles with a viable pregnancy beyond a certain gestational age (often 12 weeks). This is sometimes used as a proxy for live birth.
- Implantation rate: The percentage of transferred embryos that implant. This is rarely used in patient-facing materials because it is difficult to confirm.
When a clinic says “success rate,” ask which of these they mean. A clinical pregnancy rate will always be higher than a live birth rate from the same data.
What influences success rates?
Many factors affect IVF outcomes. Some are patient-related, some are clinic-related, and some are simply statistical.
- Female age: The strongest single factor. Younger patients generally have higher live birth rates per cycle.
- Embryo stage at transfer: Blastocyst transfers may have different rates than cleavage-stage transfers.
- Use of PGT: Preimplantation genetic testing can change which embryos are transferred and how outcomes are counted.
- Number of embryos transferred: Transferring more than one embryo can increase the chance of pregnancy but also the risk of multiples. Many clinics now prefer single embryo transfer.
- Patient selection: A clinic that accepts patients with a better prognosis will naturally report higher rates.
- Cycle cancellation: If a clinic cancels cycles before transfer, those cycles may be excluded from the denominator, inflating the rate.
- Data collection period: Rates from a single year may not reflect long-term performance.
Because these factors vary, comparing raw percentages between clinics is rarely fair. You need to know the patient mix and the definitions used.
Questions to ask a clinic about their success data
When you speak with a clinic, ask for written answers to these questions. This will help you understand their numbers and make a more informed decision.
- What exactly does your reported success rate measure? Is it clinical pregnancy, ongoing pregnancy, or live birth?
- Is the rate calculated per cycle started, per egg retrieval, or per embryo transfer?
- Does the rate include all patients, or only those under a certain age or with a certain diagnosis?
- How many patients are included in the data, and over what time period?
- Are cancelled cycles included in the denominator?
- Do you report outcomes for frozen embryo transfers separately from fresh transfers?
- Has the data been independently audited or verified?
- Can you provide age-specific success rates for patients like me?
If a clinic cannot or will not answer these questions clearly, that is useful information. It may be a sign that their marketing materials are not transparent.
How to compare clinics in Thailand responsibly
Thailand has many fertility clinics, and each may present data differently. Instead of comparing a single headline number, compare the definitions and the completeness of the data. Look for clinics that:
- Clearly state the metric they are reporting.
- Provide the time period and number of patients.
- Explain any exclusions (e.g., age limits, cancelled cycles).
- Offer age-specific data or at least a breakdown by age group.
- Are willing to discuss their results in a consultation.
You can also ask about laboratory quality, such as accreditation and embryologist experience. These factors can influence outcomes but are not captured in a single success rate. For a broader view of hospitals and clinics, see our hospital directory and editorial rankings. Our editorial policy explains how we select and present provider information.
What success rates cannot tell you
Success rates cannot predict your individual chance of having a baby. They cannot tell you how you will respond to medication, whether you will have embryos suitable for transfer, or whether you will experience complications. They also cannot tell you about the emotional and financial costs of treatment. Use success rates as one piece of information, not the whole picture.
Remember that a clinic’s overall rate may not apply to you. Your age, medical history, and previous IVF cycles all matter. A personalised assessment from a doctor is the only way to get a realistic idea of your prospects.
Next steps
Before you choose a clinic, gather information and ask questions. Here is a short checklist:
- Request written definitions of any success rates mentioned.
- Ask for age-specific data if available.
- Inquire about laboratory accreditation and embryologist credentials.
- Discuss your individual case with a doctor.
- Read our guide to IVF success rates in Thailand for more context.
Taking these steps can help you look beyond the numbers and make a decision that feels right for you.
Frequently asked questions
What is the difference between clinical pregnancy rate and live birth rate?
Clinical pregnancy rate is the percentage of cycles that result in a pregnancy confirmed by ultrasound. Live birth rate is the percentage of cycles that result in a live birth. Live birth rate is usually lower because not all clinical pregnancies progress to birth. When comparing clinics, ask which metric they are reporting.
Why do IVF success rates vary so much between clinics?
Variation can come from differences in patient age and diagnosis, the definitions used (e.g., per cycle vs per transfer), whether cancelled cycles are included, and the time period reported. A clinic with younger patients may report higher rates than one with older patients, even if the quality of care is similar.
Should I choose a clinic based only on its reported success rate?
No. Success rates are one factor among many. Consider laboratory accreditation, doctor experience, communication, cost transparency, and whether the clinic's approach fits your needs. A high success rate does not guarantee a good experience or a successful outcome for you.
How can I verify a clinic's success rate claims?
Ask the clinic for written details: the exact metric, the number of patients, the time period, and any exclusions. Some clinics may have independent audits. You can also ask for age-specific data. If a clinic is vague or unwilling to provide details, that is a red flag.
Do success rates include frozen embryo transfers?
It depends on the clinic. Some report fresh and frozen transfers separately; others combine them. Always ask whether frozen transfers are included in the number you are shown, as this can affect the rate.
Continue your research
Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.
