When undergoing fertility treatment, selecting the healthiest embryo can significantly improve the chances of a successful pregnancy. In this expert Q&A, Dr. Minoos Hosseinzadeh from the Fertility Institute of San Diego explains how PGT helps identify embryos with the best potential, reducing the risk of miscarriage and genetic disorders. Learn about the different types of Preimplantation Genetic Testing (PGT), how the process works, and who might benefit most from this advanced fertility screening.

What is Preimplantation Genetic Testing (PGT), and why is it important in fertility treatments?

Preimplantation Genetic Testing (PGT) is an advanced screening technique that allows us to analyze embryos for genetic abnormalities before implantation. It helps identify embryos with the best chance of leading to a successful pregnancy while reducing the risk of miscarriage and genetic disorders. PGT is particularly beneficial for patients with a history of recurrent pregnancy loss, advanced maternal age, or known genetic conditions. By selecting the healthiest embryos, we can improve IVF success rates and give patients the best possible outcome.

What are the different types of PGT, and who might benefit from each one?

There are three main types of PGT, each designed for specific genetic concerns:

• PGT-A (Aneuploidy Screening)
  This is a broad screening over all of 46 chromosomes looking for missing or extra chromosomes, which can lead to conditions like Down syndrome, failed implantation, or miscarriage. It’s especially helpful for patients over 35, those with recurrent pregnancy loss, or previous failed IVF cycles.
• PGT-M (Monogenic/Single-Gene Disorders)
  This screens for specific inherited diseases caused by a mutation in a single gene, such as cystic fibrosis, sickle cell disease, or Tay-Sachs. It's recommended for patients who are known carriers of genetic disorders.
• PGT-SR (Structural Rearrangements)
  This detects chromosomal translocations or other structural abnormalities that could lead to miscarriage or failed implantation. It’s ideal for patients with known chromosomal rearrangements in their family history.

The type of PGT is tailored to the patient’s unique genetic background and fertility goals.

How is PGT performed during the IVF process?

PGT is incorporated into the IVF process after egg fertilization and before embryo transfer. Here’s how it works. In the embryology lab, once a fertilized egg reaches the blastocyst stage, a small sample of cells is biopsied from the embryo. The embryo is then frozen while the biopsied cells undergo PGT testing. Based on the results, we can select the embryo with the highest chances of success. This process has been shown to reduce the risk of miscarriage and improve the likelihood of a healthy pregnancy

Is PGT safe for the embryo?

Yes! PGT is a highly refined and safe procedure. Skilled embryologists perform the biopsy using precise techniques that minimize any risk to the embryo. The cells taken are from the part of the embryo that develops into the placenta, not the portion that forms the baby. Research has shown that removing a few cells at the blastocyst stage does not affect the embryo's development, its implantation potential or cause a birth defect in children.

Does PGT guarantee a healthy baby?

While PGT significantly reduces the risk of genetic abnormalities, it does not guarantee a completely healthy baby. PGT can only screen for chromosomal or genetic conditions—it cannot detect all possible health issues or developmental conditions. However, by selecting embryos with normal chromosomal makeup, we greatly improve the chances of a successful pregnancy and a healthy baby. We always recommend additional prenatal testing during pregnancy for a comprehensive assessment.

Who should consider PGT as part of their fertility journey?

PGT is especially beneficial for:

• Women over 35, as the risk of chromosomal abnormalities increases with age
• Patients with a history of recurrent miscarriage or failed IVF cycles
• Those carrying a known genetic disorder who want to prevent passing it onto their offspring
• Patients with structural chromosomal rearrangements in their family history
• People who want an additional screening element in choosing an embryo to increase success, this often includes families working with egg donation and/or surrogacy

How does FISD make PGT testing accessible to international patients?

Since PGT-A is carried out in the embryology laboratory, it does not impact the timing or travel plans for international patients. For patients requiring other types of PGT to screen for a specific genetic disorder, FISD will collaborate with the genetics lab, genetic counsellors, and the patient’s local doctor to complete the necessary preliminary testing.