Key Highlights
- PGT is the modern umbrella term for embryo genetic testing; PGD is the older term, now mostly folded into PGT-M.
- The main difference between PGT and PGD is screening and diagnosis: PGT-A screens for chromosome number, while PGD (the older term for PGT-M) diagnoses a specific known genetic condition.
- Both tests share the same IVF and embryo biopsy process, but the lab analysis and purpose differ.
- PGT vs. PGD success rates depend on age, embryo quality, and lab expertise.
- Neither test guarantees pregnancy or a healthy child, and a fertility specialist at Bangkok Central Clinic can help determine which test best fits your situation.
If you have been researching IVF, you have probably run into PGT, PGD, PGS, PGT-A, and PGT-M in the same paragraph, often used interchangeably. However, they are not the same. PGT is the current umbrella term for genetic testing performed on embryos before transfer, while PGD is an older term that generally refers to what is now called PGT-M, which tests for a specific inherited condition already identified in a family. Each test tells you something different and specific about an embryo. If you are weighing PGT vs. PGD as part of your treatment plan, understanding the terminology first will help you make more informed decisions.
PGT vs. PGD Difference: Why the Terminology Can Be Confusing
The Evolution from PGD and PGS to PGT
Two older terms caused most of the confusion. PGD (preimplantation genetic diagnosis) was commonly used to refer to testing embryos for a specific inherited disease, and PGS (preimplantation genetic screening) was used to refer to broader chromosome screening. Reproductive medicine societies later moved to a single umbrella term, PGT (preimplantation genetic testing), and divided it into three categories: PGT-A (aneuploidy testing), PGT-M (monogenic disease testing), and PGT-SR (structural rearrangement testing).
Quick Definitions To Remember
PGT refers to genetic testing performed on embryos before transfer during IVF. PGD is the older term commonly used to test embryos for one specific inherited disease, which today is generally described as PGT-M.
PGT vs. PGD: The Core Difference
The clearest way to think about the PGT vs. PGD difference is screening versus diagnosis. PGT-A screens embryos for abnormal chromosome numbers, including extra or missing chromosomes. It does not diagnose a specific inherited disease. In plain terms, PGT-A asks: Does this embryo have the correct number of chromosomes?
Meanwhile, PGD, now generally called PGT-M, tests embryos for a known genetic mutation already identified within a family and diagnoses whether an embryo carries that specific inherited condition. In plain terms, PGT-M asks: Does this embryo carry the genetic condition this family is already concerned about?
When Is Each Type of Testing Recommended?
Who May Benefit from PGT-A?
- Advanced maternal age, generally women aged 35 and older.
- Recurrent pregnancy loss, meaning multiple miscarriages.
- Repeated IVF failure, including previous unsuccessful embryo transfers.
- Patients who want additional embryo selection information, particularly when multiple embryos are available.
Who Needs PGD/PGT-M?
- Known carriers of genetic disorders, such as thalassemia, spinal muscular atrophy, cystic fibrosis, or Huntington’s disease.
- Couples with a family history of a genetic condition.
- Patients with a disease-causing mutation already identified through prior testing.
The PGD vs. PGT Process: How Does It Fit Into Your IVF?
PGT-A and PGD (now PGT-M) both belong in the same IVF and embryo biopsy process before splitting into different lab analyses.
The process follows:
Ovarian stimulation. Multiple eggs are developed with the help of fertility medication.
Egg retrieval. Eggs are collected in a minor procedure.
Fertilization. IVF or ICSI is performed in the lab.
Blastocyst development. Embryos grow for approximately five to six days.
Embryo biopsy. A small number of cells are removed from the embryo’s outer layer.
Embryo freezing. Embryos are usually frozen while genetic results are processed.
How PGT-A Works
Preimplantation Genetic Testing for Aneuploidy (PGT-A) is performed on a small biopsy of cells taken from an embryo during an IVF cycle. This chromosome analysis is standardly performed using Next-Generation Sequencing (NGS) technology. Results generally fall into one of three categories: euploid (normal chromosome number), aneuploid (abnormal chromosome number), or mosaic (a mixed population of normal and abnormal cells).
How PGD/PGT-M Works
Rather than screening broadly, this test is built around the exact mutation already identified in the family. Results are typically reported as unaffected, carrier, or affected.
PGT vs. PGD Success Rates: What Do the Numbers Really Mean?
PGT vs. PGD success rates depend on factors like female age, embryo quality, laboratory quality, and fertility specialist expertise. Two patients with the same test can have very different outcomes based on these underlying factors.
PGT-A Potential Benefits
PGT-A may support improved implantation rates per transfer in selected patients and may reduce miscarriage risk linked to chromosomal abnormalities. These benefits vary by age and fertility history, so they should not be read as a guarantee for any individual patient.
PGD/PGT-M for Genetic Disease Prevention
The purpose of PGD/PGT-M is different: It is aimed at avoiding the transmission of a known genetic condition. Fewer embryos may qualify for transfer once the carrier or affected embryos are set aside.
Can PGT-A and PGD/PGT-M Be Combined?
In some cases, yes. Combined testing allows simultaneous chromosome screening and single-gene disease testing on the same embryo. This is sometimes discussed for patients facing advanced maternal age alongside a known genetic condition, or for couples who have had a previous pregnancy affected by a genetic disorder.
Understanding Your Genetic Testing Report: Common PGT Terms Explained
Euploid: A normal number of chromosomes.
Aneuploid: An abnormal number of chromosomes.
Mosaic: A mix of normal and abnormal cells within the same embryo.
Carrier: Carries one copy of a gene change but is not affected by the condition.
Affected: Carries the genetic condition being tested for.
Balanced translocation: A rearrangement of chromosome material that does not add or remove genetic content.
How Doctors Choose Which Embryo to Transfer: Risks, Benefits, and Considerations
Genetic results are one part of the picture. Embryo morphology, medical history, and maternal age also factor into which embryo a fertility specialist recommends for transfer.
Potential benefits include better-informed embryo selection, a reduced risk of transmitting certain inherited diseases, and reduced miscarriage risk in selected patients. At the same time, genetic testing has limits. It does not guarantee pregnancy or a healthy child, and cannot identify every possible future medical condition.
Couples often need to think through their own values around genetic testing results, including how they would approach decisions about an affected embryo and what matters most to their family. These are personal questions, and a genetic counselor or fertility specialist can help you think them through rather than make the decision for you.
Why Talk to a Fertility Specialist at Bangkok Central Clinic
Choosing between PGT-A, PGT-M, PGT-SR, or no genetic testing is a personal decision. At Bangkok Central Clinic, our fertility specialists can walk through your medical background and family history, discuss which test category applies to your situation, and create a personalized fertility plan. For couples exploring their options, learning more about preimplantation genetic testing is a good starting point before deciding what fits their treatment plan.
Book a consultation with the fertility specialists at Bangkok Central Clinic to learn whether PGT-A, PGT-M, or another genetic testing option may be appropriate for your IVF treatment plan. Our team provides comprehensive fertility solutions and professional counseling guidance throughout your journey.
References:
- Preimplantation Genetic Testing (PGT). Retrieved on 7 August 2026 from https://my.clevelandclinic.org/health/diagnostics/preimplantation-genetic-testing-pgt
- Preimplantation Genetic Testing (PGT/PGD): Embryo Screening Explained for IVF Patients. Retrieved on 7 August 2026 from https://www.wmedtour.com/blog/preimplantation-genetic-testing-pgt-pgd-embryo-screening
- Preimplantation Genetic Testing for Genetic Diseases: Limits and Review of Current Literature. Retrieved on 7 August 2026 from https://pmc.ncbi.nlm.nih.gov/articles/PMC10671162/
Frequently Asked Questions About PGT Vs. PGD Differences
Q: What is the difference between PGT and PGD?
A: PGT is the current umbrella term for genetic testing performed on IVF embryos, while PGD is an older term generally used for testing a specific known genetic condition, now typically called PGT-M.
Q: Is PGD the same as PGT-M?
A: PGD and PGT-M refer to largely the same purpose, testing for a specific inherited condition already identified in a family, though PGT-M is the terminology used in current reproductive medicine practice.
Q: Does PGT-A improve IVF success rates?
A: PGT-A may support improved implantation rates and reduced miscarriage risk in selected patients, but results vary by age and fertility history and are not guaranteed for every patient.
Q: Who should consider PGD/PGT-M testing?
A: Patients who are known carriers of a genetic disorder, have a family history of a genetic condition, or have a previously identified disease-causing mutation are typically the candidates a specialist would discuss PGT-M with.
Q: Can PGT-A and PGT-M be done on the same embryo?
A: In some cases, combined testing can evaluate both chromosome number and a specific genetic condition on the same embryo, depending on the clinical situation and lab capability.
Q: Does genetic testing guarantee a healthy baby?
A: No. Genetic testing can reduce certain risks and support embryo selection, but it does not guarantee pregnancy, a healthy child, or the detection of every possible medical condition.
