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What is Preimplantation Genetic Testing (PGT)?

If you’ve struggled to get pregnant, dealt with recurrent pregnancy loss, or are worried about passing down a genetic disease, Preimplantation Genetic Testing (PGT) can provide peace of mind before moving forward with IVF. 

What is PGT? 

PGT is a screening method for genetic diseases and chromosomal disorders. It involves screening cells from your embryos prior to transferring them as part of the IVF process. 

There are two primary types of PGT tests: preimplantation genetic testing for aneuploidy (PGT-A) and preimplantation genetic testing for monogenic diseases (PGT-M), both of which enable our fertility specialists to identify the embryos with the highest likelihood of producing a healthy baby. 

PGT-A and PGT-M: What’s the Difference? 


PGT-A stands for preimplantation genetic testing for aneuploidy. This testing involves checking an embryo for genetic conditions associated with abnormal chromosome numbers. An abnormal number of chromosomes is known as aneuploidy.Technical advancements have allowed detection of aneuploidy with 98% accuracy. 


Preimplantation genetic testing for monogenic diseases checks an embryo for specific mutations such as cystic fibrosis or sickle cell disease.

Benefits of PGS/PGD Genetic Testing

Screening embryos for genetic abnormalities has been done successfully since 1989. While it can be a hotly debated topic, it offers numerous benefits. 

Fewer pregnancy losses

Successful pregnancy requires a healthy embryo, and by identifying the healthiest embryos before implantation, you have a higher likelihood of having a healthy baby and a safe pregnancy with single embryo transfer. 

Quicker success rates

Identifying your healthiest embryos at the beginning can also help you achieve a successful pregnancy — faster. We understand that PGT is an additional expense, however it can provide a long-term payoff. IVF can place a strong physical, emotional, and financial toll on all who go through the process, so if a better understanding of the viability of your embryos early on can help reduce that stress, we are all for it!

Less uncertainty

With PGT you can significantly reduce the stress and anxiety by knowing that the embryo that you are receiving has been tested by the best available technologies. Even if you receive the heartbreaking news of genetically flawed embryos, that information can help to avoid the emotional stress of pregnancy loss or miscarriage that would have followed the embryo transfer. 

Limitations of Preimplantation Genetic Testing

Today’s screening methods allow for evaluation of all 23 pairs of chromosomes at once, achieving accuracy greater than 98%. While that can sound like a dream come true to many, there are still some limitations for you to be aware of.

Maternal Age

  • The maximum post-PGS live birth rate for women younger than 35 is 60%.
  • The live birth rate declines to 55% for women ages 35 to 40.
  • For women ages 41 to 43 the live birth rate drops to 45%.

Why does a “normal” embryo from a 35-year-old woman have a better chance to survive than a “normal” embryo from a 40-year-old? The answer lies with a condition called mosaicism, which may become more likely to occur as women grow older.


Mosaicism occurs when an embryo has two or more cell populations that have a different chromosomal makeup. Some of those cells may be abnormal, lowering the embryo’s potential for survival. During embryo biopsy, cells can be collected at only one spot, and abnormal cells may be missed if they reside elsewhere within the embryo. A mosaic embryo can recover and results in a healthy baby if the majority of its cells are normal.

Conservative Caution

If one or more of the biopsied cells is abnormal, that embryo will not be chosen for transfer. While healthy babies have been born from mosaic embryos – in one Italian study, the rate was 6 healthy babies out of 18 transfers – we remain reluctant to transfer mosaic embryos until further safety studies have been done.

As a top fertility center in the Dallas-Fort Worth area, our experienced and compassionate IVFMD team believes in making cutting-edge fertility technologies accessible to as many families as possible, while easing the financial strain at the same time. If you’re interested in preimplantation genetic testing, contact us to book your fertility assessment or speak with one of our fertility specialists. 


Sy Le, M.D.
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