When you begin IVF, you may be asked whether you want to test your embryos before transfer. One of the most common options is preimplantation genetic testing for aneuploidy, usually called PGT-A.
PGT-A is a screening test that looks at the number of chromosomes in an embryo. It can provide useful information when deciding which embryo to transfer, but it is not automatically recommended for every IVF patient.
For some intended parents, PGT-A may help guide embryo selection. For others, especially those working with a young egg donor, testing may add cost without clearly improving the overall chance of having a baby.
The right decision depends on how your embryos were created, the age of the person providing the eggs, how many embryos you have, your medical history, and your fertility specialist’s recommendations.
What is PGT-A embryo testing?
Most human cells normally contain 46 chromosomes. An embryo with the expected number of chromosomes is described as euploid. An embryo with an extra or missing chromosome is described as aneuploid.
Chromosomal abnormalities can prevent an embryo from implanting, contribute to pregnancy loss, or result in certain chromosomal conditions.
PGT-A is usually performed after an embryo reaches the blastocyst stage, typically five to seven days after fertilization. An embryologist removes a small sample of cells from the trophectoderm, the outer portion of the embryo that later contributes to the placenta.
The embryo is then frozen while the sample is analyzed by a genetics laboratory.
Results may identify an embryo as euploid, aneuploid, mosaic, or inconclusive. A mosaic result means the sample contains a mixture of cells with different chromosome findings. An inconclusive result means the laboratory was unable to provide a clear answer.
It is important to understand that PGT-A is a screening test, not a diagnostic test. It does not guarantee that an embryo will implant, that a pregnancy will continue, or that a baby will be born without health concerns.
Why do intended parents consider PGT-A?
The primary goal of PGT-A is to provide additional information that may help a fertility clinic decide which embryo to transfer first.
If several embryos are available, knowing which embryos have results consistent with the expected chromosome number may help prioritize transfers.
Age is also an important consideration. The chance of aneuploid embryos increases as the age of the person providing the eggs increases. This means PGT-A may provide different information for someone creating embryos with eggs at age 40 than for intended parents creating embryos with eggs from a younger donor.
Some intended parents also consider PGT-A because they hope to reduce the likelihood of unsuccessful transfers or certain chromosome-related pregnancy losses.
However, PGT-A cannot eliminate the possibility of a failed transfer or miscarriage. Many factors besides chromosome number affect implantation and pregnancy.
What does the research say about PGT-A?
PGT-A has become common in IVF treatment, but current research does not support routinely testing embryos for every patient.
According to the American Society for Reproductive Medicine, or ASRM, the value of PGT-A as a routine screening test for everyone undergoing IVF has not been demonstrated. Studies comparing PGT-A with conventional IVF have found similar overall pregnancy outcomes in some patient groups.
This is where an important distinction comes into play.
A euploid embryo may have a strong chance of success during an individual transfer. But that does not necessarily mean testing every embryo improves the cumulative live birth rate, which considers the chance of eventually having a baby from all embryos created during one retrieval.
The evidence that PGT-A reduces miscarriage rates is also not definitive.
For that reason, the decision should be based on the individual patient rather than treating PGT-A as a standard step everyone needs.
What are the limitations of PGT-A?
PGT-A provides information about chromosome number, but it does not screen for every possible genetic or medical condition.
For example, it does not routinely test for individual inherited disorders. Different forms of preimplantation genetic testing, such as PGT-M, may be considered when there is a known risk for a specific genetic condition.
PGT-A can also produce results that are difficult to interpret.
Mosaic embryos are one example. Because PGT-A tests only a small sample of cells, a mosaic result does not necessarily describe every cell in the embryo. Research has shown that some embryos reported as mosaic can result in healthy births, although implantation and miscarriage rates may differ depending on the type of result.
An embryo may also receive an inconclusive result, leaving intended parents with the decision of whether to consider another biopsy or proceed without additional testing.
ASRM recommends counseling before PGT-A so patients understand the possibility of mosaic, abnormal, inconclusive, and potentially inaccurate results.
Testing also adds laboratory costs and requires embryo biopsy and cryopreservation.
PGT-A when working with an egg donor
Intended parents working with an egg donor frequently ask whether they should still consider PGT-A.
Egg donors are generally younger than many patients undergoing IVF with their own eggs. Because chromosome abnormalities become more common as egg age increases, embryos created with donor eggs often have a higher likelihood of being euploid.
Current evidence does not support routinely performing PGT-A on all donor egg embryos. ASRM’s 2024 committee opinion specifically concludes that the overall evidence argues against routine PGT-A in donor egg cycles.
That does not mean testing is never appropriate.
Your fertility specialist may consider the donor’s age, how many embryos were created, sperm-related factors, your reproductive history, and your future family-building goals when discussing whether testing would provide useful information.
If you are working with an egg donor through Simple Steps Fertility, our team coordinates with your fertility clinic throughout the donor process. Medical decisions about embryo testing remain between you and your reproductive endocrinologist.
PGT-A when working with a gestational surrogate
PGT-A is also commonly discussed during gestational surrogacy journeys.
Because each embryo transfer involves significant planning, cost, and emotional investment, intended parents may want as much information as possible before deciding which embryo to transfer.
However, working with a gestational surrogate does not automatically mean your embryos need PGT-A.
The likelihood that an embryo has the expected number of chromosomes is primarily related to the egg and sperm that created it, particularly the age of the egg source. The surrogate’s age does not determine the chromosome status of the embryo.
PGT-A may help your fertility clinic prioritize embryos for transfer, but even a euploid embryo is not guaranteed to implant or result in a live birth.
The surrogate’s own medical screening and preparation for transfer remain separate and equally important parts of the process.
Questions to ask your fertility specialist
Before deciding whether to test your embryos, ask how PGT-A would affect your specific treatment plan.
Helpful questions include:
- How does the age of the egg source affect our risk of aneuploid embryos?
- How many blastocysts do we have or expect to have?
- Would the results change which embryo you recommend transferring?
- How does your clinic handle mosaic or inconclusive results?
- What are the total biopsy and testing costs?
- Would you recommend meeting with a genetic counselor?
The most useful question may simply be, “What would we do differently based on the results?”
If the answer is unclear, it may be worth discussing the benefits and limitations further before proceeding.
Should you test your embryos before transfer?
There is no single answer that is right for every intended parent.
PGT-A can provide valuable chromosome information and may help fertility specialists prioritize embryos in some IVF cycles. It may be particularly worth discussing when embryos were created using eggs from an older source or when several blastocysts are available.
For intended parents working with younger donor eggs, current evidence does not show a clear benefit from routinely testing every embryo.
The decision should consider your medical circumstances, embryo quantity, family-building goals, cost, and how the results would influence your treatment.
Most importantly, PGT-A should be presented as an option, not as a required step or a guarantee of IVF success.
How Simple Steps Fertility supports intended parents
Decisions about embryo testing are only one part of a much larger family-building journey.
At Simple Steps Fertility, we support intended parents navigating egg donation and gestational surrogacy while coordinating closely with their fertility clinic, attorneys, donors, surrogates, and other professionals involved in the process.
Your reproductive endocrinologist and genetics professionals will make medical recommendations about PGT-A and other testing. Our role is to help you understand how those decisions fit into the larger timeline and keep the different parts of your journey coordinated.
Whether you are exploring egg donation, gestational surrogacy, or both, Simple Steps Fertility can help you understand your options and what to expect at each stage.
Contact Simple Steps Fertility to learn more about building your family through egg donation and surrogacy.