At a glance
Age shapes both embryo testing results and the chance of a live birth after PGT. Learn how to read Thai clinic data by age band and what to ask before you compare.
Age is one of the strongest factors influencing both the number of usable embryos and the chance of a live birth after PGT. In Thailand, as elsewhere, clinics may report outcomes by age band, but the way those bands are defined, which patients are included, and whether the figures refer to embryos or to live births can vary widely. This guide explains how age interacts with PGT-A, PGT-M and PGT-SR, how to interpret age-stratified data from Thai clinics, and what to confirm before using any number to compare providers.
At a glance
- Age affects egg and embryo numbers, the proportion of embryos that are chromosomally normal, and the chance of a live birth.
- PGT-A, PGT-M and PGT-SR answer different questions and are not interchangeable.
- Clinic figures may be reported per cycle, per embryo transfer or per live birth, and these are not the same.
- Age bands are not standardised, so a “35–39” group at one clinic may not match another.
- PGT is not a guarantee of success and is not necessary or suitable for every patient.
Why age matters for PGT outcomes
As women age, the number of eggs retrieved in a cycle tends to decline, and the proportion of eggs with chromosomal errors tends to rise. Because PGT-A examines embryos for chromosomal number, this shift can affect how many embryos are available to test and how many are considered suitable for transfer. PGT-M looks for a specific inherited condition, and PGT-SR looks at structural chromosome rearrangements; age influences these pathways mainly through egg and embryo numbers rather than through the condition being tested.
Age also affects the chance that a transferred embryo will implant and lead to a live birth, independent of testing. This is why age-stratified data can look different from one clinic to another even when the underlying biology is similar.
How Thai clinics may present age-specific data
There is no single required format for reporting IVF or PGT outcomes in Thailand. When you see age bands, check what the number actually describes:
- Denominator: Is the figure per started cycle, per egg retrieval, per embryo transfer, or per patient?
- Numerator: Is it a positive pregnancy test, a clinical pregnancy, an ongoing pregnancy, or a live birth?
- Population: Does it include all patients in that age band, or only those who reached a specific stage?
- Testing type: Are PGT-A, PGT-M and PGT-SR results combined, or reported separately?
- Time period: Which years are included, and have laboratory methods changed since then?
Two clinics can report the same underlying outcomes but appear very different because of these choices. This is why a single percentage is rarely enough to compare providers fairly.
Reading age bands without overinterpreting them
Age bands are a convenience, not a biological threshold. A woman who turns 35 does not suddenly change category in a meaningful way; the underlying trend is gradual. When you read a table of age-specific outcomes, keep these points in mind:
- Small age bands with few patients can produce unstable percentages that shift year to year.
- Wide bands, such as “35 and over”, can hide important differences within the group.
- Outcomes for PGT-A may be reported per embryo tested, per transfer, or per cycle, and each answers a different question.
- Clinic-level data may not reflect your individual situation, including ovarian reserve, prior cycles, sperm factors, uterine factors or the reason for testing.
PGT-A, PGT-M and PGT-SR: different questions, different data
It helps to separate the three main types of preimplantation genetic testing when you look at outcomes:
| Test | What it looks for | How age mainly interacts |
|---|---|---|
| PGT-A | Chromosome number (aneuploidy screening) | Fewer eggs and more chromosomally abnormal embryos with increasing age |
| PGT-M | A specific inherited condition | Affects the number of embryos available to test, not the condition itself |
| PGT-SR | Structural chromosome rearrangements | Affects the number of embryos available and the proportion that are balanced |
Because these tests answer different questions, age-stratified data for one should not be used to estimate outcomes for another.
What PGT can and cannot tell you
PGT can provide information about the embryos tested, but it does not guarantee a pregnancy, a live birth or a healthy child. Testing may reduce the chance of transferring an embryo with a specific chromosomal or genetic finding, but it cannot eliminate all risk. Some conditions are not detected by the test used, and some embryos may be classified as uncertain or mosaic, which requires careful counselling.
PGT is also not necessary or suitable for every patient. Whether it is offered depends on the clinical question, the number of embryos available, laboratory capability and the patient’s preferences after counselling.
Practical questions to ask a clinic in Thailand
When you review age-specific PGT data or discuss your own case, these questions can help you interpret what you are told:
- How do you define the age bands in your reports, and why?
- Are your figures per cycle, per transfer or per live birth?
- Do you report PGT-A, PGT-M and PGT-SR separately?
- How do you handle embryos with uncertain or mosaic results?
- What proportion of your patients in my age group reach embryo transfer?
- How do you counsel patients when the number of embryos available for testing is low?
- What alternatives to PGT do you discuss, and in what circumstances?
Next-step checklist
- Clarify your own clinical question: are you considering PGT-A, PGT-M or PGT-SR, and why?
- Ask the clinic to explain the denominator and numerator behind any age-specific figure they share.
- Request counselling on the limitations of testing, including the possibility of uncertain results.
- Discuss how age, ovarian reserve and prior history may affect your own expected number of embryos.
- Confirm what is included in any quoted cost and what is not, without relying on a single figure.
- Ask how the clinic handles legal, consent and documentation requirements, and confirm these directly with the clinic and relevant authorities.
Related reading
Frequently asked questions
Does PGT improve success rates for older women?
PGT-A can provide information about the chromosomal status of the embryos tested, which may help some patients and their clinicians decide which embryo to transfer. However, it does not guarantee a live birth, and its effect on overall success depends on many factors, including the number of embryos available. Age remains an important influence on outcomes regardless of testing.
Why do Thai clinics report different success rates for the same age group?
Clinics may use different age bands, different definitions of success (for example, pregnancy versus live birth), different denominators (per cycle, per transfer or per patient), and different inclusion criteria. Laboratory methods and the time period covered can also differ. These choices can make figures look different even when underlying outcomes are similar.
Is PGT suitable for everyone doing IVF in Thailand?
No. PGT is not necessary or suitable for every patient. Whether it is offered depends on the clinical question, the number of embryos available, laboratory capability and patient preferences after counselling. Your clinic can explain whether testing is relevant to your situation.
What does a mosaic PGT result mean?
A mosaic result means the embryo has a mix of cells with different chromosomal findings. The implications can be complex, and clinics may handle these results differently. Ask your clinic how they counsel patients about mosaic embryos and what options they discuss.
Can I compare PGT success rates between clinics in Thailand?
Comparison is difficult unless the clinics report outcomes in the same way. Ask each clinic to explain the denominator, numerator, age bands and time period behind their figures. Even then, clinic-level data may not predict your individual outcome.
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.
Need help turning research into a shortlist?
