The Role of Preimplantation Genetic Testing for Aneuploidies (PGT-A) in In Vitro Fertilization

In vitro fertilization (IVF) has revolutionized reproductive medicine, allowing millions of couples around the world to achieve their dream of having a baby. However, not all embryos lead to a successful pregnancy. Chromosomal abnormalities are one of the leading causes of implantation failure, miscarriage, and genetic diseases. This is where Preimplantation Genetic Testing for Aneuploidies (PGT-A) comes into play, enhancing IVF success rates and providing patients with greater peace of mind throughout the process.
In this article, we will explore in detail what PGT-A is, how it works, its benefits, and why it can be a crucial tool in fertility treatments.

What is Preimplantation Genetic Testing (PGT-A)?

PGT-A is an advanced embryo screening technique performed during the IVF process. Its primary goal is to identify chromosomal abnormalities (aneuploidies) in embryos before they are transferred to the uterus. This allows the selection of embryos with the correct number of chromosomes, increasing the chances of achieving a successful pregnancy and reducing the risk of miscarriage.
The human body has 23 pairs of chromosomes, and any alteration in this number can lead to embryo development failure. For example, Down syndrome occurs when there is an extra copy of chromosome 21 (trisomy 21). With PGT-A, specialists can detect these abnormalities before implantation, offering an invaluable opportunity to prevent genetic diseases.

How Does PGT-A Work?

The PGT-A process is integrated with IVF and carried out in several stages:

1. Ovarian Stimulation and Egg Retrieval
   The IVF process begins with ovarian stimulation, where hormones are administered to induce the development of multiple follicles. Once the eggs reach maturity, follicular aspiration is performed to extract them.
2. Fertilization and Embryo Development
   The retrieved eggs are fertilized with sperm in the laboratory, resulting in embryos that are cultured for 5 to 7 days until they reach the blastocyst stage.
3. Embryo Biopsy
   At this stage, 5 to 10 cells are extracted from the trophectoderm (the outer layer of the blastocyst that will form the placenta). This procedure is safe and does not affect embryo development. The extracted cells are sent for genetic analysis while the embryo is vitrified (frozen) until the results are obtained.
4. Genetic Analysis
   The analysis evaluates the chromosomal count of each embryo, identifying whether they have the correct number (euploidy) or present abnormalities (aneuploidy). Only euploid embryos are selected for transfer.

Benefits of PGT-A in IVF

PGT-A offers multiple benefits that can significantly impact fertility treatment outcomes:

1. Increased Implantation Rates
   Selecting embryos with a normal chromosomal complement significantly increases implantation rates. A euploid embryo has a higher likelihood of successfully implanting in the uterus, reducing failed attempts.
2. Reduced Risk of Miscarriage
   Chromosomal abnormalities are the leading cause of miscarriage during the first trimester. By transferring chromosomally normal embryos, the risk of pregnancy loss is drastically reduced.
3. Prevention of Genetic Diseases
   PGT-A detects embryos with chromosomal abnormalities linked to conditions such as Down syndrome, Turner syndrome, or Klinefelter syndrome, minimizing the risk of genetic diseases in the baby.
4. Fewer Transfers Required
   By identifying viable embryos from the outset, the need for multiple embryo transfers is reduced, optimizing patients' time and resources.

Who Can Benefit from PGT-A?

Although PGT-A is not mandatory for all IVF cycles, certain patients can greatly benefit from this procedure:

• Women over 35 – The incidence of chromosomal abnormalities increases with age, making PGT-A especially useful in reducing the risk of aneuploidies.
• Patients with recurrent miscarriages – PGT-A can identify healthy embryos, decreasing the likelihood of consecutive miscarriages.
• Repeated IVF failures – For those who have experienced unsuccessful IVF cycles, PGT-A can help identify viable embryos, improving success rates.

Carriers of genetic diseases – Couples with a family history of genetic conditions can benefit from selecting healthy embryos through PGT-A.

PGT-A vs. Other Types of Genetic Testing

PGT-A should not be confused with other types of preimplantation genetic testing:

• PGT-M (Preimplantation Genetic Testing for Monogenic Diseases): Detects specific genetic diseases caused by mutations in a single gene.

PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements): Evaluates issues in chromosomal structure, such as inversions or translocations.
PGT-A focuses exclusively on detecting aneuploidies, helping select chromosomally normal embryos.

Conclusion

Preimplantation Genetic Testing (PGT-A) has transformed in vitro fertilization, providing patients with greater opportunities for success and reducing risks associated with chromosomal abnormalities. For many couples, it represents a key tool in their journey toward parenthood.
If you are considering IVF treatment, speaking with your fertility specialist about PGT-A could be the first step toward a successful and healthy pregnancy.