Genetic Testing

Understanding PGT

What PGT-A Actually Tests

Standard PGT-A looks at 46 data points — the 23 chromosome pairs — to check whether an embryo has the correct number of chromosomes. That is it. It does not look at the rest of the embryo's DNA, and it does not tell you whether an embryo will implant or result in a live birth.

There are invisible factors inside an embryo that no current test can detect — mitochondrial dysfunction, epigenetic abnormalities, and damage from fragmented sperm DNA among them. An embryo can have the correct number of chromosomes, develop all the way to blastocyst, pass PGT testing, and still carry invisible defects that prevent it from implanting or developing further.

This is exactly why optimizing sperm health before a retrieval matters so much. Sperm DNA fragmentation, elevated A1c, poor morphology — these are factors that affect the invisible architecture of the embryo in ways that PGT simply cannot see. A chromosomally normal embryo built from damaged sperm DNA may look perfect on paper and still fail. No test currently available will catch that. The only way to address it is to optimize sperm health before the embryos are ever made.

Not All Results Are Equally Reliable

This is something most clinics don't explain clearly:

• Uniform whole-chromosome aneuploid calls — most reliable. These are the results you can trust most.
• Euploid calls (normal) — generally reliable but not a guarantee of implantation or live birth
• Mosaic calls — significant uncertainty. Up to 50% of embryos labeled mosaic have been shown to actually be euploid when rebiopsied. Do not discard a mosaic embryo without getting a second opinion.
• Segmental aneuploid calls — A 2026 study (Al Hashimi et al.) reanalyzed 105 segmental aneuploid blastocysts and found that 81% were actually mosaic. In more than one third of cases a second biopsy would have changed the embryo's classification entirely.

If your embryo is labeled mosaic or segmental aneuploid — do not discard it without getting a second opinion. Talk to your clinic about how they handle mosaic results, seek out additional medical opinions, and research the latest data before making any decisions. Note: while rebiopsy is sometimes discussed as an option, there are real concerns about the impact of additional freeze and thaw cycles on embryo quality. This is a nuanced decision that deserves careful conversation with your care team — not a reflexive one.

Is PGT Right for You?

PGT is not automatically the right choice for everyone:

• Age of the egg source matters more than your own age — if you are using a young donor's eggs, the case for PGT is weaker than your clinic may suggest
• Younger patients with no specific genetic concerns have a weaker case for routine PGT than clinics often imply
• Religious or ethical considerations — mini IVF or untested transfers are legitimate options

Questions worth asking before deciding:

• How old is the egg source?
• Have we ruled out uterine factors before assuming the embryo is the problem?
• What is the concordance rate for mosaic and segmental results at your specific lab?
• What is your clinic's policy on transferring mosaic embryos?
• If I get a segmental aneuploid result what are my options?

The Class Action Lawsuits — What You Should Know

Former IVF patients have filed class action lawsuits against several major genetic testing companies — including CooperGenomics, CooperSurgical, Natera, Igenomics, and others — alleging consumer fraud and breach of warranty for selling PGT-A without disclosing that the test is unproven and experimental. The lawsuits allege that as of 2024 there have been no randomized properly structured non-commercial trials to support claims that PGT-A improves implantation rates, increases pregnancy and live birth rates, or reduces miscarriages.

These lawsuits are still working through the courts. But the fact that they were filed — and that the companies named include labs used at major clinics across the US — is information worth having before spending thousands of dollars on testing.

What Europe Says

ESHRE — the European Society of Human Reproduction and Embryology, one of the most respected reproductive medicine bodies in the world — classifies PGT-A as not recommended for routine clinical use. PGT-A is banned outright in Germany, France, and the Netherlands.

The Lab Your Clinic Uses Matters

Most clinics have a default PGT lab. You are allowed to ask about alternatives.

• Juniper Genomics — A newer company using whole genome sequencing plus transcriptome sequencing, analyzing approximately 12 billion data points per embryo versus 46 for standard PGT-A. They examine individual cells separately rather than in bulk, which directly addresses the mosaicism misclassification problem. I was personally interested in using them for my CNY retrieval but ultimately used Igenomics. I cannot speak to Juniper from firsthand experience — but the science behind their approach is compelling and worth researching.
• Igenomics — The lab I personally used for my CNY retrieval. My PGT results from this cycle are shared on the Real Data page.

You can ask your clinic to use a different PGT lab. It is worth asking — especially if you have concerns about your clinic's default lab or have had mosaic or segmental results you want a second opinion on.

The Bottom Line on PGT

This is not a recommendation to test or not test. It is a recommendation to go in fully informed. PGT costs thousands of dollars per cycle, is not covered by most insurance, is the subject of active class action litigation, is not recommended for routine use by European regulatory bodies, and has not been shown in rigorous trials to improve live birth rates across the general IVF population.

It may have value in specific situations. But it is not the straightforward tool that many clinics present it as. Ask hard questions before you pay for it.

Resource: Remembryo.com (Embryoman) — one of the best sources for staying current on PGT research in plain language.