Preimplantation Genetic Testing for Aneuploidy (PGT-A) has become an increasingly common tool in assisted reproductive technology (ART), especially for couples undergoing in vitro fertilization (IVF) or working with a surrogate. By screening embryos for chromosomal abnormalities before transfer, PGT-A aims to increase the chances of a successful, healthy pregnancy. But is it right for everyone?
In this comprehensive guide, we explain what PGT-A is, how it works, who should consider it, and what the latest research tells us about its effectiveness and limitations.
What Is PGT-A?
PGT-A stands for Preimplantation Genetic Testing for Aneuploidy, formerly known as PGS (Preimplantation Genetic Screening). It is a laboratory procedure performed on embryos before they are transferred into the uterus. The goal is to detect chromosomal aneuploidies—embryos with too few or too many chromosomes—that can lead to failed implantation, miscarriage, or genetic disorders like Down syndrome.
PGT-A differs from:
- PGT-M, which tests for specific inherited diseases (monogenic disorders),
- PGT-SR, which screens for structural chromosomal rearrangements.
Why Is PGT-A Performed?
The main purposes of PGT-A include:
- Selecting chromosomally normal embryos (euploid) for transfer
- Reducing the risk of miscarriage
- Improving implantation and live birth rates
- Avoiding transferring embryos with conditions like trisomy 21 (Down syndrome)
A study published in Fertility and Sterility (2019) found that PGT-A increased implantation rates in patients aged 35 and older by over 15% compared to non-screened embryos.
Who Should Consider PGT-A?
PGT-A Pass Rates by Age Group
One of the strongest predictors of whether an embryo will be chromosomally normal is the age of the woman who produced the egg. The older the woman, the more likely her eggs will have chromosomal abnormalities. The chart below shows the approximate PGT-A (formerly PGS) pass rates by age group, based on large-scale data from a genetic testing laboratory:
- Egg Donors (typically under 30): 64%
- Under 35 years old: 57%
- 35–37 years old: 49%
- 38–40 years old: 37%
- 41–42 years old: 24%
- Over 42 years old: 16%
This data illustrates why PGT-A is often recommended for women over 35 and why donor eggs—especially from younger donors—tend to produce higher-quality embryos with better chances of success.
While PGT-A can be considered by any IVF patient, it is especially recommended for:
- Women over 35 years old
- Couples with recurrent pregnancy loss
- Patients with repeated failed IVF cycles
- Intended parents using donor eggs and wishing to minimize risk
- Parents undergoing surrogacy, especially with only one or two embryos to transfer
- Families who wish to select the sex of their baby for family balancing or personal reasons
PGT-A may also be considered in cases where intended parents want to electively transfer a single embryo (eSET) to reduce the risks associated with multiple pregnancies.
In a 2021 meta-analysis published in Human Reproduction Update, researchers found that live birth rates were significantly higher in the PGT-A group among women aged 35 and older, but the difference was not significant in women under 35.
The PGT-A Process: Step-by-Step
- Egg retrieval and fertilization via IVF
- Embryo development to blastocyst stage (Day 5-7)
- Trophectoderm biopsy: 5–10 cells are carefully removed from the outer layer of the embryo (not the part that becomes the fetus)
- Embryo vitrification (freezing)
- Genetic analysis using NGS (Next-Generation Sequencing)
- Embryo transfer based on results, selecting a euploid embryo
The results typically take 7–10 days, and embryos remain frozen until transfer.
Understanding PGT-A Results: What Your Report Means
When you receive your PGT-A report, the results typically categorize each embryo into one of several classifications:
- Euploid: This embryo has the correct number of chromosomes (46 total). These embryos are considered the most likely to result in a successful pregnancy and are usually prioritized for transfer.
- Aneuploid: This embryo has an abnormal number of chromosomes (e.g., 45 or 47), indicating a full chromosomal gain or loss. These are usually not recommended for transfer due to a high risk of miscarriage or birth defects.
- Mosaic: This embryo contains both normal (euploid) and abnormal (aneuploid) cells. The degree of mosaicism may be classified as low-level (20–40%) or high-level (40–80%). Some clinics may consider transferring low-level mosaic embryos under close monitoring, though success rates may be lower and risks higher.
- Segmental Aneuploidy: This means a portion of a chromosome (rather than an entire chromosome) is duplicated or deleted. The significance depends on the size and location of the affected segment. Interpretation is more complex and often requires genetic counseling.
- No Result / Inconclusive: Sometimes, the biopsy sample is insufficient or fails during testing. In such cases, clinics may offer to re-biopsy or consider the embryo as untested.
Understanding your PGT-A report requires guidance from a reproductive endocrinologist or genetic counselor who can assess the clinical implications and help you decide which embryos are most suitable for transfer.
How Accurate Is PGT-A?
PGT-A is generally over 95% accurate in detecting full chromosomal aneuploidies, according to the American Society for Reproductive Medicine (ASRM). However, it’s not infallible. Limitations include:
- False positives/negatives: For example, we once worked with a pair of intended parents who transferred a PGT-A normal embryo into a surrogate. The pregnancy began normally, but during the second-trimester anatomy scan, the fetus was found to have a severe congenital heart defect. Amniocentesis later confirmed Trisomy 18 (Edwards syndrome). This case highlights that PGT-A, while highly accurate, is not 100% foolproof.
- Mosaicism: when the embryo contains both normal and abnormal cells. Some mosaic embryos may still result in healthy live births
- Potential discarding of viable embryos due to uncertain results
Risks and Limitations
- Embryo damage risk during biopsy (minimal with modern techniques)
- Cost, as PGT-A is not always covered by insurance
- Emotional impact: discarding embryos due to abnormal results
- PGT-A does not test for all diseases—it only looks at chromosome numbers, not gene-level mutations (unlike PGT-M)
Cost of PGT-A in the U.S.
PGT-A is an out-of-pocket expense for many families. Here’s what to expect:
- Testing for up to 6 embryos: $3,000 – $6,000
- Each additional embryo: ~$250–$400
- Some fertility clinics bundle PGT-A into their IVF packages
Surrogacy journeys that include PGT-A may incur higher upfront costs but potentially reduce the cost of failed transfers or miscarriage later.
Ethical and Emotional Considerations
PGT-A raises questions that intended parents should consider carefully:
- What happens to embryos labeled as abnormal or mosaic?
- Do we transfer lower-quality embryos if no euploid ones are available?
- Are we comfortable with the idea of embryo selection?
Some religious or ethical frameworks may discourage or prohibit embryo testing. However, for many, PGT-A provides peace of mind.
PGT-A in Surrogacy and Egg Donation
While egg donors do not undergo PGT-A themselves, embryos created from donor eggs are often tested via PGT-A. This is especially common when:
- Intended parents are transferring embryos to a surrogate
- There are multiple embryos, and selecting the “best” one increases chances of success
- Parents want to reduce uncertainty, especially when using a high-cost donor cycle
In short: PGT-A enhances the efficiency of egg donation and surrogacy, even if it doesn’t involve the donor directly.
Conclusion: Is PGT-A Right for You?
PGT-A is a powerful tool in the IVF and surrogacy journey—but it’s not a guarantee, and it’s not for everyone. For older patients, those with failed IVF cycles, or families using donor eggs or a surrogate, PGT-A may improve outcomes and reduce risk.
Always speak with a fertility specialist and genetic counselor before deciding whether PGT-A is a good fit for your family-building plan.
Key Takeaways
- PGT-A helps identify chromosomally normal embryos, improving IVF success rates, especially for women over 35.
- Embryo classification includes euploid, aneuploid, mosaic, segmental aneuploidy, and “no result.”
- Even with PGT-A, rare false negatives or mosaic results can affect pregnancy outcomes.
- Intended parents using surrogates or donor eggs frequently choose PGT-A to reduce uncertainty.
- Cost varies by clinic and embryo count, with most tests ranging from $3,000 to $7,000.
- Not all embryos with mosaic or segmental results are discarded—some may still be viable with counseling.
- PGT-A doesn’t guarantee a healthy baby but can reduce risk when used appropriately.
FAQ
1. What is PGT-A?
PGT-A (Preimplantation Genetic Testing for Aneuploidy) is a genetic test on IVF embryos to screen for chromosomal abnormalities before transfer.
2. Who benefits most from PGT-A?
Women over 35, couples with multiple IVF failures or miscarriages, and those using donor eggs or surrogates often benefit most.
3. What does a PGT-A report show?
Embryos are labeled as euploid, aneuploid, mosaic, segmental, or “no result.” Each category has unique implications for embryo transfer.
4. Is PGT-A always accurate?
PGT-A is highly accurate (>95%) but not perfect. False results and mosaicism can still lead to uncertainty.
5. How much does PGT-A cost?
Typically $3,000 to $7,000 depending on the number of embryos tested and your clinic.
6. Can I use PGT-A with donor eggs or surrogacy?
Yes. It’s common to use PGT-A with donor egg embryos before transferring to a surrogate.
7. Can PGT-A determine baby’s gender?
Yes. PGT-A reveals sex chromosomes and is often used for gender selection in family balancing.
📚 References
- Forman EJ et al. Fertility and Sterility, 2019.
- Greco E et al. New England Journal of Medicine, 2015.
- Mastenbroek S et al. Human Reproduction Update, 2021.
- ASRM Practice Committee Guidelines, 2023.
- Capalbo A et al. Reproductive Biomedicine Online, 2020.
💬 Have Questions About PGT-A? We’re Here to Help.
At Ivy Surrogacy, we understand how complex and emotional the IVF journey can be—especially when it comes to making decisions about genetic testing. If you’re wondering whether PGT-A is right for you, or how it fits into your surrogacy or donor egg plan, our experienced team is happy to guide you.
Reach out today for a personalized consultation, and let’s talk about the best path forward for your family.
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Medically reviewed by Dr. Diana LeBlanc, MD – Reproductive Endocrinologist at Hanabusa IVF
