PGT-A
PGT-A, preimplantation genetic testing for aneuploidy, checks each embryo for whole missing or extra chromosomes. A few cells are taken from the outer layer on day five, the embryo goes into the freezer, and a laboratory reports back on which embryos look chromosomally normal. Aneuploidy is the single biggest reason embryos fail to implant or miscarry, and it becomes far more common as eggs age.
What the test does is sort. It does not change any embryo; it ranks the batch you already made, so the embryos most likely to work are transferred first. Where it helps, it helps by shortening the road: fewer transfers and fewer miscarriages on the way to a baby.
It is worth understanding its limits too. A biopsy is a handful of cells from the layer that becomes the placenta, not the baby, and it is read as though it speaks for the whole embryo. Results come back mosaic, meaning a mixture, often enough to be a category of its own, and embryos labelled abnormal have occasionally gone on to become healthy babies. Whether it raises the chance of a live birth per cycle started is still debated, so it suits some people much more than others, and this page is about working out which you are.
At a glance
- Also known as
- Preimplantation genetic testing for aneuploidy, PGT-A, PGS, embryo screening, chromosome screening
- Appointment time
- Biopsy on day five in the laboratory; results in 1–3 weeks
- Back to normal
- None beyond the cycle itself
- Typical cost
- $3,000–$6,000 per cycle, typically $1,000–$2,500 setup plus $200–$500 per embryo (United States, self-pay)
- Usually preceded by
- IVF
Figures reviewed .
On this page
Who it’s for
The argument is strongest where a large share of embryos is expected to be abnormal, because that is where ranking them saves the most time. In practice that means eggs collected in the late thirties or forties, recurrent miscarriage where chromosomes are the suspected cause, repeated implantation failure after good-looking embryos went back, and a known chromosomal rearrangement in one partner, which is a related but different test.
It also needs a batch. Testing is worth considering when there are several blastocysts to rank. With one or two the ranking has nowhere to go, the fixed laboratory fee is charged anyway, and a single abnormal result can leave you with nothing to transfer from a cycle that would otherwise have had something.
It is usually less useful for younger patients with good embryos. Under thirty-five most blastocysts are chromosomally normal, so the test mostly confirms what was already likely, and an imperfect reading could set aside a viable embryo. For a first cycle with no history of loss, most people do just as well without it.
There is no separate eligibility. If you are having IVF you can have this, though the law differs by country and sex selection for social reasons is prohibited in most of Europe, the UK, Australia and Thailand. See eligibility across fertility treatment.
Before you agree to testing
Ask which decision the result would actually change for you. If the answer is that you would transfer the same embryos in roughly the same order anyway, you know you can comfortably skip it.
How it’s done
The decision has to be made before egg collection, because it changes how the whole cycle is handled. Most laboratories insist on ICSI for fertilisation, so stray sperm on the outside of the egg cannot contaminate the result. That is a second fee, so factor it into the budget.
Embryos are then grown to day five or six. Only blastocysts can be biopsied, because until then there is no outer layer to take cells from, so any embryo that stops growing earlier never reaches the test. The embryologist opens a small hole in the shell with a laser and draws off roughly five to ten cells from the trophectoderm, the layer that will become the placenta. The cells from the inner group that becomes the baby are not touched.
Each embryo is then vitrified immediately and stored. This is why testing forces a freeze-all cycle, and why a fresh transfer is off the table once you have chosen it. The biopsied cells go to a genetics laboratory, which amplifies the small amount of DNA and counts the chromosomes, usually by next-generation sequencing.
Results come back in one to three weeks in three flavours. Euploid, meaning the expected twenty-three pairs. Aneuploid, meaning a whole chromosome missing or extra. And mosaic, meaning the sample contained both normal and abnormal cells, which the laboratory grades by how much. You then plan a frozen embryo transfer with the euploid embryos first.
When the consent forms arrive
Read what the form says happens to mosaic and abnormal embryos, and check whether it lets you keep them. Consent is signed early, the question only becomes real weeks later, and it is much easier to choose the options you want while you have time to think.
After PGT-A
Nothing physical happens to you at all. The biopsy happens to an embryo in a laboratory several days after your egg collection, and everything you feel belongs to the cycle rather than to the test. What changes is the shape of the wait.
A cycle without testing ends with a transfer inside a week of collection, or a freeze and a plan. With testing there is a second wait, one to three weeks, while the laboratory reports on each embryo. It helps to plan for it.
It is also worth knowing that some batches come back with no euploid embryos. That happens more often with older eggs and small batches, and it is not a verdict on the whole cycle. It is information about that batch, from a test with a margin of error, and the next cycle can read differently.
| Before stimulation | Testing is agreed and consent signed. ICSI is usually added to the plan at this point. |
|---|---|
| Collection day | Eggs collected as in any cycle. Nothing about the collection changes because of the test. |
| Days 5–6 | Blastocysts are biopsied and frozen the same day. Embryos that never reach blastocyst are not tested. |
| Week 1 after | Samples are at the genetics laboratory. Nothing to do and nothing to report. |
| Weeks 1–3 | Results arrive as a list: euploid, aneuploid or mosaic, embryo by embryo. |
| The results conversation | Which embryos to transfer, in what order, and what happens to the mosaic ones. Worth booking properly rather than taking by phone. |
| 4–8 weeks after | A frozen transfer of a euploid embryo, with the lining prepared medicated or natural. |
Before the results arrive
Decide in advance what you would do with a mosaic embryo, and book a proper appointment to discuss the results rather than taking them on the phone. A mosaic result is best understood in a proper conversation rather than as a number.
Risks and complications
The risk specific to the test is a wrong answer about a good embryo. Five cells are read as a proxy for a hundred or more, and the outer layer is not always identical to the inner one. Embryos reported aneuploid have been transferred, in studies and by accident, and some have produced healthy babies. How often that would happen is not known, because those embryos are usually not transferred.
Mosaic results are the practical version of this problem. A decade ago they were reported as abnormal. Now they are a category with its own guidance, and transferred mosaic embryos do produce healthy live births at lower rates than euploid ones. Current practice is to grade and counsel on mosaics rather than discard them, so it is worth asking your clinic's policy.
The biopsy itself is a small physical risk to the embryo. Done by an experienced laboratory it appears not to reduce survival or implantation meaningfully. Which is why the laboratory's experience is the thing to ask about.
Two more practical points. Testing means a freeze-all, so the transfer moves to a later cycle. And a cycle can end with no embryo cleared for transfer, which is worth having talked through before you decide.
PGT-A results
It helps to be precise about what the evidence shows. What is well established is that euploid embryos implant more often and miscarry less often than untested ones on average. A transfer of a tested euploid blastocyst has a better chance than a transfer of an unselected one. Clinics quote that figure and it is real.
What is in dispute is whether testing improves your chance of a baby from the cycle as a whole. The larger randomised trials have not shown a clear gain in live birth per cycle started, and in younger patients some have pointed the other way. The reason is the arithmetic. Selecting a better embryo raises the odds per transfer and removes embryos from the pool, and over the whole batch those two effects push against each other.
For context, live birth per frozen blastocyst transfer is generally quoted at roughly a quarter to a third where the eggs were young, and tested euploid transfers sit above that. That shows the selection works; what it means for the cycle as a whole depends on your batch.
Where there is more agreement is on time and on miscarriage. Testing tends to reduce the number of failed transfers before a successful one, and reduce miscarriages along the way. For someone who has had two losses, that is worth a great deal even if the eventual live birth rate is unchanged. That is the real strength of the test, and it is what I would base the decision on.
Alternatives to PGT-A
The default alternative is transferring embryos in the order a good embryologist ranks them by how they look and how they grew. Morphology and timing are less precise than a chromosome count, but free, and over a batch they get most people to broadly the same place, a little more slowly.
Where recurrent loss is the problem, other investigations compete for the same money. Chromosome testing of both partners, a check on the shape of the uterus, thyroid and clotting tests. A single-gene or translocation test is a different product from PGT-A and answers a different question, and if one of you carries a rearrangement that is the test you want.
And where several cycles have produced no usable embryos, donor eggs are the option that genuinely changes the picture. Testing explains what happened; donor eggs change the odds.
Frozen Embryo Transfer
A transfer of an embryo that was frozen after an earlier collection, thawed and placed in the uterus weeks or years later. No stimulation, no egg collection and no anaesthetic, with the lining prepared either by hormones or by your own cycle.
Best for: anyone with embryos in storage, and anyone whose clinic froze everything rather than transferring fresh
IVF
Conventional IVF, where the ovaries are stimulated to produce a batch of eggs, the eggs are collected under sedation and mixed with sperm in the laboratory, and one embryo is transferred. The core treatment that the other pages in this group are variations on.
Best for: anyone whose tubes, sperm or time make natural conception unlikely, and who wants the treatment with the best odds per attempt
Combining PGT-A with other treatment
PGT-A arrives bundled with ICSI and a frozen embryo transfer, for the reasons under how it's done. Both are worth planning for as part of the decision.
Other testing can be run on the same biopsy. Where a partner carries a chromosomal rearrangement or a single-gene condition, those tests use the same cells and are usually priced together. That is the version of embryo testing with the clearest benefit, because it answers a specific, known question.
Testing works best with a good-sized batch, so it is rarely paired with a mild or natural cycle.
PGT-A cost
PGT-A is charged in two parts, so make sure you hear both. There is a laboratory setup or handling fee per cycle, and then a price per embryo tested, sometimes in bands of up to eight. A cycle with six blastocysts costs more to test than a cycle with two, so the bill is not knowable when you agree to it.
Then the related costs. ICSI, if you would not otherwise have had it. Freezing and a year of storage, because nothing goes back fresh. A frozen transfer fee that a fresh cycle would not have paid. Add those up for the true total, which is usually well above the quoted testing price.
It is rarely funded. NHS-funded cycles do not include PGT-A for age alone, and most insurance treats it as elective. Regulators in several countries rate the evidence for it as limited, which is useful background to read before a consultation.
Ask for the whole figure. Handling fee, per-embryo price at the number of embryos you might realistically have, ICSI, freezing, storage and the transfer. Then ask what happens to the fee if no embryo reaches blastocyst and nothing gets tested.
| Country | Self-pay | Public / insurance |
|---|---|---|
| United States ICSI, freezing, storage and a frozen transfer are all additional and usually required by it | $3,000–$6,000 per cycle, typically $1,000–$2,500 setup plus $200–$500 per embryo | Rarely covered; most plans treat it as elective even where they fund IVF |
| United Kingdom Testing for a known inherited condition is a different service and is sometimes funded | £2,500–£4,000 per cycle including a handful of embryos | Not funded for age alone; the regulator rates the evidence as limited and requires clinics to say so |
| Europe Spain, Czechia and Greece offer it routinely; rules on mosaic transfer differ by country | €2,000–€4,000 per cycle | Rarely funded; several countries restrict what may be tested for |
| Thailand Often bundled into package pricing; sex selection is prohibited and cannot be reported | $2,000–$4,500 per cycle | Self-pay only for international patients |
Read more: IVF
Choosing a clinic for PGT-A
You are choosing two laboratories: the clinic's own, and the genetics lab it uses. Ask which genetics laboratory the samples go to, what platform it uses, and what proportion of its results come back with no readable answer. A good laboratory keeps its no-result rate to a few per cent.
Then ask the embryology side. How many biopsies they do a year, what their blastocyst survival after biopsy and warming is, and who performs them. Plenty of experience is what you are looking for.
The question that reveals the most is what they do with mosaic embryos. A clinic that can describe grading them, counselling on them and transferring the ones worth transferring is working to current guidance. And ask directly whether they would recommend testing for someone your age with your history. A clinic that tailors the answer to you is the one to trust.
At the consultation
Ask them to tell you about a cycle where testing left a patient with nothing to transfer. A clinic that talks you through it openly is one that will help you decide well, and it is the outcome most worth thinking through in advance.
Clinics that do PGT-A
Frequently asked questions
Does PGT-A improve my chances of a baby?
Per transfer, yes. Per cycle started, the larger trials have not shown a clear gain, especially in younger patients. Its clearest benefit is fewer failed transfers and miscarriages. See results.
Can a normal embryo be reported abnormal?
Occasionally. The biopsy is a few cells from the outer layer, and some embryos reported abnormal have produced healthy babies. See risks.
What does a mosaic result mean?
That the sample held both normal and abnormal cells. Mosaic embryos are transferable and do produce live births, at lower rates than euploid ones. See risks.
Can I still have a fresh transfer?
No. Every biopsied embryo is frozen while the results come back, so testing commits you to a frozen transfer.
Does it check for anything other than chromosome numbers?
Not on its own. Single-gene conditions and inherited rearrangements need different tests, which can be run on the same biopsy. See alternatives.