PGT-A and IVF: What It Is, How It Works, and Who May Benefit

If you’re considering IVF, you’ve probably heard your fertility specialist mention PGT-A, or Preimplantation Genetic Testing for Aneuploidy. One of the most common questions I hear is:

“Should I have my embryos genetically tested?”

The answer depends on your individual situation. PGT-A is an important tool in modern fertility care, but it’s not the right choice for every patient. Understanding what it does—and what it doesn’t do—can help you make an informed decision.

What is PGT-A?

PGT-A is a genetic screening test performed on embryos created through in vitro fertilization (IVF). Its purpose is to identify embryos with the normal number of chromosomes before they are transferred into the uterus.

Humans normally have 46 chromosomes, arranged into 23 pairs. We inherit half from the egg and half from the sperm. Chromosomes contain our DNA and carry the genetic instructions needed for normal growth and development.

An embryo with the correct number of chromosomes is called euploid. An embryo with extra or missing chromosomes is called aneuploid.

Chromosomal abnormalities are the most common genetic abnormality found in human embryos and are a leading cause of failed implantation, miscarriage, and certain chromosome disorders, such as Down syndrome.

Why do chromosome abnormalities happen?

Most chromosome abnormalities occur by chance when eggs or sperm are formed. Although either parent can contribute, the majority originate from the egg, making maternal age the single biggest factor affecting embryo chromosome health.

As women age, the percentage of chromosomally normal embryos decreases.

Approximate rates of embryo aneuploidy are:

• Under 35 years: 25–40%
• 35–37 years: 40–50%
• 38–40 years: 50–70%
• 41–42 years: 70–80%
• Over 42 years: More than 80%

This is one of the primary reasons fertility declines and miscarriage rates increase with age.

It’s important to remember that PGT-A does not improve embryo quality. Instead, it helps identify which embryos already have the highest chance of resulting in a healthy pregnancy.

How is PGT-A performed?

Embryos are grown in the IVF laboratory for five to seven days until they reach the blastocyst stage.

At that point, an embryologist carefully removes approximately 5–10 cells from the embryo’s outer layer, called the trophectoderm. These cells will eventually form the placenta—not the baby itself.

The embryo is then frozen while the biopsy sample is sent to a specialized genetics laboratory. Using advanced technologies such as Next Generation Sequencing (NGS), the laboratory evaluates whether the embryo has the expected number of chromosomes.

Understanding the Results

Most embryos are reported as one of three categories:

Euploid: The embryo has the expected number of chromosomes and generally has the highest chance of implantation and live birth.

Aneuploid: The embryo has an abnormal number of chromosomes and is much less likely to result in a healthy pregnancy.

Mosaic: The embryo contains a mixture of normal and abnormal cells. Some mosaic embryos can still result in healthy pregnancies, but decisions regarding transfer require individualized counseling.

Who may benefit from PGT-A?

PGT-A is not recommended for everyone undergoing IVF. However, it may be particularly helpful for patients with:

• Advanced maternal age
• Recurrent pregnancy loss
• Multiple failed IVF cycles
• A previous pregnancy affected by a chromosome abnormality
• Multiple embryos available for selection
• A desire to reduce unsuccessful embryo transfers

The decision should always be individualized after discussing your medical history and reproductive goals with your fertility specialist.

Coming Next

In Part 2, we’ll discuss what the latest research says about PGT-A, review the current ASRM guidelines, explain its limitations, and answer one of the most common questions patients ask: Does PGT-A guarantee a healthy pregnancy?

Does PGT-A Improve IVF Success? What the Evidence and ASRM Guidelines Say

In Part 1, we discussed what PGT-A is and how it works. Now let’s answer the question most patients want to know:

Does PGT-A improve my chances of having a baby?

The answer depends on what outcome you’re measuring.

What does the research show?

Over the past decade, numerous studies have evaluated whether PGT-A improves IVF outcomes.

Research consistently shows that transferring a euploid embryo results in higher implantation rates and lower miscarriage rates than transferring an embryo with an abnormal number of chromosomes.

PGT-A may also:

• Reduce unsuccessful embryo transfers
• Decrease miscarriage caused by chromosomal abnormalities
• Shorten the time to pregnancy for some patients
• Support single embryo transfer, reducing the risk of twins while maintaining excellent success rates

However, one important finding often surprises patients.

Although PGT-A improves the selection of embryos for transfer, studies have not consistently shown that it increases the cumulative live birth rate for every patient undergoing IVF. In other words, it may make treatment more efficient without increasing the overall chance of having a baby in all patient populations.

What do the ASRM Guidelines recommend?

The 2024 American Society for Reproductive Medicine (ASRM) Committee Opinion concludes that PGT-A should not be routinely recommended for every IVF patient.

Instead, ASRM recommends an individualized approach based on factors such as:

• Maternal age
• Previous IVF outcomes
• Pregnancy history
• Number of embryos available
• Patient goals and preferences

The greatest benefit appears to be in carefully selected patients rather than universal use for all IVF cycles.

What are the limitations of PGT-A?

PGT-A is an excellent technology, but it remains a screening test not a diagnostic test.

Several important limitations exist:

• Only a small number of cells are tested.
• Those cells come from the future placenta, not the fetus itself.
• Some embryos are mosaic, meaning different cells within the embryo have different chromosome patterns.
• False-positive, false-negative, and inconclusive results can occur, although they are uncommon.

PGT-A also does not detect every genetic condition. It cannot diagnose most inherited diseases, birth defects, autism, or developmental disorders. Different testing, such as PGT-M, is required for known single-gene disorders.

Does embryo biopsy harm the embryo?

Modern trophectoderm biopsy performed by experienced embryologists is considered very safe. Improvements in biopsy techniques, laboratory culture systems, and embryo vitrification have significantly reduced the risk of damaging embryos.

Like any medical procedure, no intervention is completely risk-free, but embryo biopsy has become a routine part of IVF care in experienced laboratories.

Do I still need prenatal testing?

Yes.

Even after transferring a euploid embryo, professional societies continue to recommend routine prenatal screening and, when appropriate, diagnostic testing such as chorionic villus sampling (CVS) or amniocentesis.

No screening test is 100% accurate, and prenatal testing remains the gold standard for confirming fetal chromosome status during pregnancy.

The Bottom Line

PGT-A is one of the most valuable tools available in modern IVF, helping physicians identify embryos with the greatest likelihood of implantation and healthy pregnancy.

For many patients particularly those of advanced maternal age or those with recurrent pregnancy loss it can improve the efficiency of IVF and reduce unnecessary embryo transfers. However, it is not appropriate for everyone, and current ASRM guidelines recommend an individualized approach rather than routine testing for all patients.

Every fertility journey is unique. The decision to pursue PGT-A should be made after reviewing the latest evidence and discussing your specific goals with your reproductive endocrinologist.