PGTA: The Promise, the Hype, and the Reality — Part I
Written by Helen Yang, PhD
Founder & CEO, OvaVision
You’re sitting in the clinic, staring at the embryologist’s report.
“Two embryos tested normal. One mosaic. The rest abnormal.”
The words sound scientific, maybe even comforting. Finally, something measurable in the chaos of IVF. A test that seems to offer certainty, to separate the “good” embryos from the “bad.”
But what if that certainty isn’t what it seems?
🧬 The Evolution of Genetic Testing in IVF
So how did we get here? How did a once-rare lab technique become one of the most common (and expensive) add-ons in modern IVF? To understand PGTA, you first have to go back to the beginning — to the origins of genetic testing in the IVF lab.
In the 1990s, doctors began using a method called preimplantation genetic diagnosis (PGD) to help families who have history of serious inherited diseases like cystic fibrosis or Tay-Sachs. These individuals carried one copy of a faulty gene but were healthy themselves, and their children have a chance of inheriting the diseases. The goal of PGD was straightforward: identify embryos carrying known mutations and transfer only the unaffected ones. It was targeted, purposeful, and often life-changing.
Over time, that same technique evolved into what’s now called PGT-M (Preimplantation Genetic Testing for Monogenic disorders) — essentially a modernized version of PGD that still focuses on specific, known conditions passed down within families.
As technology advanced, researchers wondered if they could use similar methods not just to avoid known genetic diseases, but to screen embryos for chromosomal abnormalities — having extra or missing chromosomes that might cause miscarriage or implantation failure. That idea became preimplantation genetic screening (PGS), later renamed PGTA (Preimplantation Genetic Testing for Aneuploidy).
The promise was irresistible: test embryos for the number of chromosomes, pick the “normal” ones, and improve IVF success.
Over the next decade, PGTA spread quickly. What began as a niche tool soon became routine. Many clinics now recommend it broadly, even for patients without genetic risk factors.
For many, it feels like progress — science making IVF more predictable. But as PGTA became standard faster than the evidence matured, a quiet question began to surface:
Does it actually help?
🔮 The Early Promise of PGTA
When PGTA first appeared, it seemed like the next great leap in IVF.
For patients, it offered a sense of certainty — the sense that something finally made IVF more predictable. For clinics, it promised better outcomes, fewer miscarriages, and fewer failed transfers.
The concept felt beautifully simple: by testing embryos before transfer, doctors could identify which ones had the correct number of chromosomes — the “healthiest” embryos — and discard the rest. Because theoretically, those without the right number of chromosomes wouldn’t be viable at all.
Early studies and marketing materials suggested that this approach could dramatically increase success rates. Some clinics began presenting PGTA as a near-essential step, especially for older patients or anyone wanting to “maximize” each IVF cycle.
And on paper, it makes sense. Chromosomal abnormalities are a major cause of miscarriage and implantation failure. So it’s easy to see why a test that screens for those abnormalities became so appealing — to both doctors and patients who desperately wanted some control in a process that often feels random.
But as the years went on and more data emerged, that early optimism began to meet reality. What once seemed like a breakthrough revealed a more complicated story — because biology is rarely that straightforward. As with most things in reproductive science, the truth proved far more nuanced, and far less black and white. The simple promise started to look a little too good to be true.
🪞 When Promise Meets Reality
As PGTA became more common, the results didn’t always match the marketing.
Many patients who tested all their embryos found themselves with none labeled “normal.” Others transferred only “normal” embryos but still faced failed cycles or miscarriages.
When researchers began comparing outcomes, a different pattern started to emerge. Across large studies, PGTA has not consistently improved live birth rates — and in some cases, it’s been linked to lower cumulative success. That’s because embryos labeled “abnormal” are often discarded, even though some of them could have developed into healthy pregnancies.
PGTA may help in specific situations — for example, in older patients or couples with recurrent miscarriage — but for most IVF patients, it doesn’t move the needle.
Now, as the science finally catches up with the marketing, researchers are uncovering many reasons why. One reason is that PGTA sometimes finds mosaic embryos — embryos made up of a mix of normal and abnormal cells. For years, no one knew how to interpret those results. Some clinics treated mosaics as abnormal and discarded them. Others transferred them only as a last resort.
Today, most experts consider mosaic embryos to fall somewhere in between: lower priority than chromosomal “normal” embryos, but higher than clearly “abnormal” ones. Even so, the reality is more complicated than those labels suggest — a story we’ll return to in Part II.
The data show what biology has always reminded us: development isn’t binary. Embryos aren’t simply “good” or “bad.” They’re complex, living, and dynamic systems, and a single snapshot of PGTA can’t capture the full picture.
PGTA is by no means useless — it’s that its limits were never clearly explained. For a test sold as certainty, its results have turned out to be anything but.
💨 Smoke and Mirrors: Common Misconceptions About PGTA
But wait, if PGTA isn’t proven to improve success rates, how is it marketed so confidently? Isn’t it FDA-approved? Isn’t someone making sure these claims are true?
Those are fair questions — and the reality is complicated.
PGTA isn’t an FDA-approved medical test. It’s what’s known as a lab-developed test, or LDT — a category that allows certified labs to offer genetic testing without formal FDA review. That loophole means there’s no federal agency verifying whether the test actually does what it promises.
Clinics can market PGTA as “advanced science,” but the data behind it doesn’t have to meet the same standards as regulated medical devices. It’s legal — but misleading. And that’s how a procedure still under scientific debate became a near-routine part of IVF.
That lack of oversight has also led to confusion about what PGTA actually measures.
One of the most common misunderstandings is that it screens for Down syndrome. It doesn’t. Down syndrome is caused by a specific chromosomal difference — trisomy 21, when there are three copies of 21st pair of chromosome instead of two. PGTA doesn’t diagnose Down syndrome or any other genetic disorder. It simply looks at a small group of cells from an early embryo to estimate whether the overall number of chromosomes appears typical.
That distinction matters. A “normal” PGTA report doesn’t mean an embryo is free from genetic disease, and an “abnormal” result doesn’t guarantee it would have developed a condition. The test gives a snapshot — not a diagnosis.
PGTA was never designed to diagnose disease, yet it’s often treated as if it can. Over time, the lines between different types of genetic testing in IVF have blurred, leaving patients — and sometimes even clinicians — unsure what these results really mean. What began as a precise tool for detecting known genetic conditions has become a source of false reassurance, giving the appearance of certainty where none exists.
As the conversation around PGTA evolves, one thing is becoming clear: the science hasn’t fully caught up with the marketing. In Part II, we’ll explore why these results are so hard to interpret, what “mosaic embryos” really mean, and how regulation — long overdue — may finally begin to catch up with the technology itself.
About the Author
Dr. Helen Yang, PhD, is a Harvard-trained scientist with years of experience in cutting-edge fertility research. She founded OvaVision to bring people AI-driven insights into their fertility journey, with a focus on clarity, emotional support, and science that actually makes sense.
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