PGT-A vs PGT-M: Which Embryo Test Do You Actually Need?

Ever wondered what the difference between PGT-A and PGT-M is, and if/why you need both?

Both are preimplantation genetic testing, but they don’t cover for each other. A clean PGT-A result says nothing about inherited disease, and a clean PGT-M result says nothing about chromosomes. And neither can promise you a healthy pregnancy or a baby.

PGT-A screens every embryo for the right number of chromosomes. PGT-M tests embryos for one specific inherited gene mutation you already know about.

Most IVF patients are offered PGT-A. You need PGT-M only if carrier screening or family history has flagged a specific genetic disease.

This article explains what each test looks for, how to tell which one applies to you, and what the evidence says about running them together, including why your age changes that answer more than anything else does.

PGT-A vs PGT-M: The Differences at a Glance

Every difference in that table comes out of one distinction: PGT-A sorts your embryos by probability, PGT-M gives a yes or no on one named mutation. Preimplantation genetic testing (PGT) is the umbrella term covering both, which is part of why they get confused in the first place.

That distinction also explains the misunderstanding we correct most often in consultations. Euploid doesn’t mean healthy. A normal chromosome count says nothing about the genetic abnormalities PGT-M is built to find.

PGT-M can’t start until the genetics lab builds a test for your exact mutation, and that build needs DNA from the genetic parents, sometimes from affected relatives too. Because the build is priced separately from the analysis, it’s the biggest reason PGT testing costs within an IVF cycle vary so much from one patient to the next.

If you’re using a donor egg or donor sperm, the probe is built around whoever provided the genetic material, so we need the donor’s carrier status before your cycle rather than during it. Reputable donor programs screen for this, and it’s one of the first things we confirm when someone plans an egg donation cycle with a known family mutation. It’s the step most likely to hold up a timeline when nobody thought to ask.

What PGT-A Tests For

Its full name is preimplantation genetic testing for aneuploidy (PGT-A). You’ll also see it called aneuploidy screening, or PGS, the name it went by before. It counts the embryo’s chromosomes to check the number is right.

The arithmetic confuses almost everyone, because different clinics quote different numbers. PGT-A analyses all 24 chromosome types that exist in humans: numbers 1 through 22, plus the X and Y sex chromosomes. Any single embryo carries 23 pairs, 46 chromosomes in total.

Aneuploid is the word you’ll hear on your results call. It means an embryo has an extra chromosome or is missing one. These chromosomal abnormalities are the same mechanism behind Down syndrome and Turner syndrome, which is part of why the term lands so hard when nobody has explained it first.

These errors are almost always random. They didn’t come from your family, and they aren’t anyone’s fault. They become more common as egg quality declines with age, which is a leading reason cycles fail in older patients.

Patients are usually surprised by the next part. Across the IVF population, PGT-A has not been shown to raise cumulative live birth rates. It can screen embryos and rank them. It can’t improve them. The American Society for Reproductive Medicine’s 2024 guidance found recent trials produced similar pregnancy outcomes with and without the test, and concluded that “the value of PGT-A to lower the risk of clinical miscarriage is also unclear.” Where it does help is in ordering your transfers, and in one group in particular, covered further down.

What PGT-M Tests For

If you’re here for PGT-M, you already know the name of the thing you’re trying to avoid. That’s what makes this test different from the other one.

Its full name is preimplantation genetic testing for monogenic conditions, and it was called preimplantation genetic diagnosis, or PGD, until the terminology changed. It looks for single gene disorders already known to run in the family, which means the lab has to know exactly what it’s hunting before it can hunt. PGT-M can’t find a disease nobody has named.

Patients most often come to us about cystic fibrosis, Tay-Sachs disease, sickle cell anemia, spinal muscular atrophy, Huntington’s disease, hemophilia, Duchenne muscular dystrophy and thalassemia, along with BRCA1 and BRCA2, which carry an increased risk of breast and ovarian cancer. If a condition has a known, named mutation, a probe can usually be built to identify embryos that carry it.

How many of your embryos are likely to be affected depends on how these genetic conditions are inherited:

• Autosomal recessive, where both genetic parents carry it: roughly 25% of embryos affected.
• Autosomal dominant, where one parent carries it: roughly 50% affected.
• Sex-linked, such as Duchenne muscular dystrophy or hemophilia: roughly 50% of male embryos affected.

If you carry a dominant mutation, expect around half your embryos to be affected before chromosome testing enters the picture at all. We tell patients that number before retrieval rather than after, because it changes how many cycles you plan for, and because nobody should learn it on the phone in the middle of a hard week.

One limit to know now rather than later: PGT-M is highly accurate but not infallible. Misdiagnosis after PGT-M has been reported at 0.07%, 12 cases across 2,538 cycles, and it is why ASRM and SART recommend you be offered confirmatory prenatal testing in a pregnancy conceived after PGT-M. We’ll raise that with you at the time.

Which Test Applies to You

When PGT-A Is the Right Test

PGT-A comes up in four situations:

• Advanced maternal age, where aneuploidy rises as egg quality declines.
• Recurrent or unexplained miscarriage, with a caveat below that we think you should read.
• Unexplained IVF failure, whether that means failed cycles or failed transfers.
• A known chromosomal translocation, Robertsonian or reciprocal, which usually points to PGT-SR instead.

Meeting one of those doesn’t settle whether you’re eligible for PGT-A, but it’s where the conversation starts.

The miscarriage caveat is the one nobody mentions. ASRM’s 2026 guidance on recurrent pregnancy loss puts aneuploidy behind roughly 50 to 60% of first-trimester miscarriages. But compared with someone who has had a single loss, patients with recurrent loss are more likely to be having euploid miscarriages, where the chromosomes were normal. In the group most often sent for PGT-A, chromosomes turn out to be the explanation less often than that headline number suggests. That makes a proper recurrent pregnancy loss workup more useful than another test.

PGT-A is the default add-on almost everywhere. We don’t treat it that way. ASRM’s 2024 review found the clearest signal in older patients: a post hoc analysis of the STAR trial showed higher ongoing pregnancy rates per embryo transfer in the 35 to 40 group, though the advantage did not hold when measured from the start of the cycle rather than from transfer. For women over 37, ASRM cites one study putting the number needed to treat at 21 retrieval cycles, or 35 embryo transfers, for one additional live birth. That is a real benefit and a demanding one. Not everyone needs IVF, and not everyone doing IVF needs PGT-A.

When PGT-M Is the Right Test

PGT-M applies when you already know what you’re looking for. That usually means one of three things:

• Carrier screening found the same recessive mutation on both sides.
• You carry a dominant mutation, whether or not it has affected your own health.
• There’s a known genetic disease in your family, or you already have a child with an inherited condition.

PGT-M is not a general safety net. It targets specific genetic disorders you have already named, and it answers nothing beyond them.

One group deserves a direct word. If you’re here because of BRCA1 or BRCA2, you may be perfectly fertile. You’re doing IVF for access to the testing, not because you can’t conceive, and that’s a completely legitimate reason to be sitting in our office.

What Carrier Screening Does Not Catch

Standard expanded carrier screening panels are built around autosomal recessive and X-linked conditions. Autosomal dominant conditions sit outside what they were designed to find.

ACMG’s Tier 3 panel, the one it recommends for anyone planning a pregnancy, covers 113 genes: 97 autosomal recessive disorders and 16 X-linked.

The logic behind leaving dominant conditions out is that anyone carrying one would already know, because it usually shows up in the family. That holds most of the time. It fails if you were adopted, if your family is small or you’re out of touch with it, if a condition can be carried without ever causing symptoms, or if the mutation started with you.

A clean carrier screening result rules out a specific list of recessive and X-linked conditions. It isn’t an all-clear on everything else, because the panel never looked. Genetic screening only finds what it was built to find. If there’s a pattern in your family that yours never explained, raise it with a fertility specialist before you build embryos. That conversation costs nothing and we’d rather have it early.

When You Need PGT-SR Instead

Some patients comparing PGT-A and PGT-M are choosing between the wrong two options.

PGT-SR covers structural rearrangements. If you carry a balanced translocation or inversion, all your genetic material is present but arranged differently, and you’re probably healthy yourself because nothing is missing. You produce embryos that are often unbalanced, though, and the problem usually surfaces as repeated miscarriage rather than as anything wrong with your own health.

PGT-A counts chromosomes. PGT-SR checks how they’re arranged, which is a different question entirely. If you’re a translocation carrier, counting alone won’t tell you what you need to know.

Do You Need Both PGT-A and PGT-M?

One Biopsy Covers Both Tests

The fear is a second biopsy. There isn’t one. A single biopsy sample covers both analyses.

The PGT process is the same either way, and it runs inside a standard in vitro fertilization cycle. We grow your embryos to the blastocyst stage, day 5 or 6, then take a few cells from the trophectoderm, the outer layer that becomes the placenta rather than the inner cell mass that becomes the baby. That sample goes to the genetics lab for genetic analysis while we freeze the embryos by vitrification. You come back for a frozen embryo transfer once the genetic status of each embryo is known.

Sequential testing is an option worth raising with us: PGT-M first, then PGT-A on only the embryos that pass. Same single biopsy, lower total spend when you expect a large share of embryos to be affected. The trade-off is turnaround, closer to a month than two weeks, and not every genetics lab offers it. Ask about it if you’re carrying a dominant mutation and bracing for half your embryos to be ruled out.

The Case for Adding PGT-A

The strongest argument is that you’re already biopsying. Adding PGT-A is an analysis fee, not a second procedure.

What it’s meant to buy is fewer transfers that were never going to work. A transfer that fails costs you a month, a medicated cycle, and a very hard week. Sparing you one of those is supportable. Preventing a miscarriage you would otherwise have had is not, and ASRM says so itself.

If you end up with several normal embryos, PGT-A tells us which to transfer first. That ordering is the actual product.

You should hear the other half before you decide. Two large registry analyses associate PGT-A with lower cumulative live birth rates in routine practice, not higher. One drew on 133,494 US cycles in patients aged 40 and under. The other covered 111,975 UK treatment episodes, of which 2,243 involved PGT-A. Both are retrospective, so neither proves cause. The benefit is genuinely contested, which is exactly why we decide this one patient at a time.

The Case Against, and Why Your Age Changes the Answer

ASRM’s 2024 committee opinion is direct: “At present, however, the routine use of blastocyst biopsy with aneuploidy testing in all infertile patients undergoing IVF treatment cannot be recommended.”

For PGT-M patients specifically, a 2022 analysis in the Journal of Assisted Reproduction and Genetics went further, concluding that PGT-M without PGT-A is preferred to achieve an unaffected live birth. It’s a single-author paper rather than a professional body position, so it carries less weight than ASRM, but it addresses this exact question.

Its argument rests on the observation that PGT-M patients skew young, often under 35, an age where aneuploidy is less common. If that describes you, the miscarriage risk PGT-A is meant to reduce is already low. Against that small gain sits a real cost: discarding an embryo on an abnormal result that didn’t reflect what that embryo could have become.

That cost mostly lives in mosaicism, and you should understand it before you consent to anything. A biopsy reads a handful of cells and infers the whole embryo from them. Embryos can be mosaic, carrying both normal and abnormal cells, so the cells sampled may not represent the embryo they came from. A mosaic result isn’t a clean pass or fail. It’s a maybe, delivered about an embryo you may have very few of. ASRM issued separate guidance in 2023 on managing mosaic results, and clinics still differ in how they classify these embryos and whether they’ll offer one for transfer. Ask yours directly. Our PGT specialists will give you our policy before you consent to anything, not after a result forces the question.

If you’re under 35, carrying a known mutation, with good ovarian reserve and no history of loss, adding PGT-A is a judgment call rather than an automatic yes. The case gets stronger with age, and with failed transfers nobody has been able to explain. It cuts the other way if diminished ovarian reserve has left you with two or three embryos, because discarding one on an uncertain result costs you proportionally more. And it gets weaker if your history is recurrent miscarriage, for the reason we covered earlier.

This is an open scientific question. Anyone who answers it confidently in either direction is telling you more than the evidence knows.

Your Genetics Are Specific. Your Testing Plan Should Be Too.

Four questions to ask any clinic before you consent to testing:

• How do you classify and handle mosaic embryos, and would you offer one for transfer?
• Can PGT-M and PGT-A run sequentially off the same biopsy here, and what does that do to turnaround?
• How long does building the custom PGT-M probe take, and whose DNA samples do you need?
• Given my age, my ovarian reserve and my history, what does the evidence say about PGT-A adding value for me?

We welcome all four, and the fourth one especially. Twenty years and more than 3,000 babies is what lets us answer it from our own outcomes rather than from the literature alone. Our IVF success rates run at roughly twice the national cumulative average, we’re CAP and AAAHC accredited and a SART member clinic, and Newsweek named us one of America’s Best Fertility Clinics in 2023 and 2024.

Book an appointment with our team. Our fertility specialists will go through your carrier screening results and your medical history, and tell you which testing actually fits your cycle.