By Dr. Francisco Arredondo | Founder and Medical Director, Pozitivf | May 2026
When you’re in the middle of an IVF cycle, the list of decisions can feel overwhelming. Medications, timing, retrieval protocols — and then, at some point, someone mentions PGT-A: Preimplantation Genetic Testing for Aneuploidies. It sounds complicated. It has a price tag. And it raises a question many people are hesitant to ask: do I actually need this?
I’m going to answer that as directly as I can — because in my experience, patients who understand what PGT-A testing is make better decisions about it.
What Is PGT-A Testing, Exactly?
PGT-A stands for Preimplantation Genetic Testing for Aneuploidies. During a standard IVF cycle, embryos are cultured in the lab for five to six days until they reach what is called the blastocyst stage. At that point, a small number of cells — typically five to eight — are biopsied from the outer layer of the embryo.
This outer layer, called the trophectoderm, is the part that becomes the placenta, not the fetus itself.
The biopsied cells are sent to a genetics laboratory, where all 24 chromosomes — 22 autosomes plus X and Y — are analyzed to determine whether the embryo has the correct number of chromosomes.
A chromosomally normal embryo is called euploid. One with an abnormal chromosome count is called aneuploid. Aneuploid embryos are the leading cause of IVF failure, failed implantation, and first-trimester miscarriage. They can result in conditions like Down syndrome (trisomy 21) or Turner syndrome (monosomy X), among others that are incompatible with a healthy pregnancy.
What PGT-A does is identify which of your embryos are euploid before transfer — so your care team can prioritize the ones most likely to result in a healthy pregnancy.
The 20% Factor: Why Chromosome Status Changes Everything
Here is a number worth noting: selecting a chromosomally normal embryo for transfer can improve the likelihood of a successful transfer by approximately 20% compared to transferring untested embryos of similar morphological appearance.
Without genetic testing, embryos are selected based on how they look under a microscope. An embryo that appears perfect can be aneuploid. An embryo that appears less ideal can be chromosomally normal. Appearance, in this case, can be misleading.
That 20% improvement is not trivial. For someone who has already experienced failed transfers or pregnancy losses, it can represent the difference between having answers and experiencing more uncertainty.
Note: Outcomes vary by individual. PGT-A does not guarantee a successful pregnancy. Your care team can help interpret what the data means for your specific situation.
Who Is PGT-A Testing Most Likely to Benefit?
PGT-A is not for everyone — and a good fertility specialist will tell you that directly. The decision should be based on your medical history, your embryo count, and your goals.
The patients who tend to benefit most include:
- People aged 35 and older, since chromosomal error rates in eggs increase significantly with age
- Those with a history of recurrent pregnancy loss — two or more miscarriages
- Those who have experienced repeated IVF failures despite transferring morphologically good embryos
- People with a known chromosomal translocation in themselves or their partner
- Those who want to reduce the time to a successful pregnancy by prioritizing the best embryo first
For younger patients — typically under 35 — with no history of loss or failed cycles, the benefit of PGT-A is less clear-cut. Some studies show similar outcomes whether or not testing is performed in this group. This is an important part of the conversation your care team should have with you.
How Does the Embryo Biopsy Work — and Is It Safe?
The biopsy removes cells from the trophectoderm — the outer layer that becomes the placenta. It does not touch the inner cell mass, which becomes the fetus. When performed by an experienced embryologist, the procedure is considered safe, and studies have not shown a meaningful increase in adverse outcomes in children born from biopsied embryos.
Embryos are typically vitrified — flash-frozen — immediately after biopsy while genetic results are awaited, and transferred in a subsequent cycle. The vitrification process used today preserves embryo integrity far better than older slow-freeze techniques.
What Happens If All My Embryos Are Aneuploid?
This is a difficult reality that some patients face, particularly those with fewer eggs retrieved or who are in older age brackets. It is also one of the most important pieces of information PGT-A can provide.
Knowing that all available embryos are aneuploid — while painful — allows you and your care team to make an informed decision about next steps: another retrieval cycle, donor eggs, or other paths to parenthood. Transferring aneuploid embryos without that knowledge often results in failed transfers or losses that take both emotional and financial tolls without ever providing the “why.” Information, even hard information, is better than prolonged uncertainty.
What PGT-A Cannot Tell You
PGT-A tests chromosome number — that is its scope. It does not screen for all genetic diseases. Single-gene disorders such as cystic fibrosis, sickle cell disease, or BRCA mutations require a different test called PGT-M (Preimplantation Genetic Testing for Monogenic disorders). If you have a known heritable condition in your family, that is a separate and important conversation with your care team.
PGT-A also cannot guarantee implantation or a successful pregnancy. A euploid embryo transferred to a receptive uterus gives you the best available starting point — but biology is not perfectly predictable.
Mosaic Embryos: Understanding the Gray Zone
Some embryos come back as mosaic — meaning they contain a mix of chromosomally normal and abnormal cells. Mosaic embryos occupy a clinical gray zone. They are generally not the first choice for transfer, but they are not automatically disqualified.
In the absence of fully euploid embryos, mosaic embryos — particularly those with low-level mosaicism in specific chromosomes — can be transferred with appropriate counseling. This is why having a care team that communicates results clearly matters. A mosaic result is not a dead end; it is a conversation.
PGT-A at Pozitivf: Transparent, Included, Explained
At Pozitivf, our PGT-A package is designed around one principle: you should know exactly what you are paying for and what it includes before you begin. One all-in price covers the biopsy, the genetics lab, the results consultation, and the Programmed Embryo Transfer — so you are not assembling a bill from multiple providers after the fact. No matter the amount of embryos.
More importantly, every result is explained to you in plain language by your care team. Understanding what PGT-A testing is in theory is useful. Understanding what your specific results mean for your next decision is what actually matters.
Frequently Asked Questions
What is PGT-A testing and how is it different from standard IVF? Standard IVF involves fertilizing eggs and selecting embryos for transfer based on how they look under a microscope. PGT-A adds a genetic analysis step: a small biopsy is taken from each embryo at the blastocyst stage, and all 24 chromosomes are analyzed to determine whether the embryo has the correct number. This allows the care team to prioritize chromosomally normal (euploid) embryos for transfer, rather than relying on appearance alone.
Does PGT-A guarantee a successful pregnancy? No — and any clinic that suggests otherwise should be approached with caution. PGT-A significantly improves the quality of information available when selecting embryos, and transferring a euploid embryo gives you a better starting position. But implantation depends on many factors, including uterine receptivity, endometrial health, and individual biology. PGT-A improves the odds; it does not eliminate uncertainty.
At what age does PGT-A become most important? The aneuploidy rate in eggs increases substantially with age. Studies show that by age 40, approximately 60–80% of embryos may be aneuploid — compared to roughly 20–30% in patients under 35. For this reason, PGT-A tends to offer the most clinical value for patients aged 35 and older, particularly those with a history of failed transfers or pregnancy loss.
Can a mosaic embryo result in a healthy baby? Yes — mosaic embryos have resulted in healthy births, though they are generally considered second priority behind fully euploid embryos. The clinical decision depends on the degree of mosaicism, which chromosomes are affected, and whether euploid alternatives are available. This is always an individualized conversation with your care team, never a blanket policy.
Ready to understand what PGT-A could mean for your specific situation?→ pozitivf.com/fertility-care-options
