Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT) is an advanced genetic screening technique performed on embryos created through IVF treatment.
Its purpose is to analyse the genetic makeup of an embryo before it is transferred to the uterus, helping to reduce the risk of chromosomal abnormalities and inherited genetic conditions in future offspring.

Thanks to PGT, reproductive decisions can be made with greater confidence and more comprehensive information,helping to support reproductive decision-making, reduce genetic uncertainty, and lower the risk of transmitting certain inherited genetic conditions.

What Is Preimplantation Genetic Testing (PGT)?

PGT is a genetic analysis performed on embryos at the blastocyst stage, typically when they have reached day 5 or day 6 of development in the laboratory.
At this stage, a small number of cells are carefully removed from the embryo through a procedure known as embryo biopsy.

These cells are then sent to a specialised genetics laboratory for analysis, while the embryo is safely preserved through vitrification until the genetic results become available. This procedure allows specialists to evaluate whether an embryo presents:

Chromosomal abnormalities.
Inherited genetic disorders.
Genetic alterations that may compromise embryo viability or the progression of pregnancy.

What Is Embryonic Genetic Testing Used For?

Preimplantation Genetic Testing can help to:

Select genetically viable embryos.
Reduce the risk of miscarriage.
Decrease the likelihood of implantation failure.
Prevent the transmission of known inherited genetic disorders.
Improve ongoing pregnancy rates in selected patient groups.

The purpose of PGT is not to guarantee pregnancy, but to reduce genetic uncertainty before embryo transfer takes place.

Types of Preimplantation Genetic Testing

PGT is not a single test, but rather a group of genetic studies that are recommended according to each patient’s clinical situation.
Every type of PGT requires prior genetic assessment and a clear medical indication.

PGT-A: Chromosomal Screening

PGT-A analyses the number of chromosomes within an embryo.
It is particularly useful for detecting aneuploidies (abnormal chromosome numbers), which become more common with advancing maternal age.

PGT-M: Monogenic Genetic Disorders

PGT-M is recommended when one or both intended parents are carriers of a specific inherited genetic condition that could be passed on to their children.
This allows embryos to be screened for a particular genetic disorder before transfer.

PGT-SR: Structural Chromosomal Rearrangements

PGT-SR is designed for patients with known structural chromosomal abnormalities, such as:

Translocations.
Inversions.

The test helps identify embryos that have inherited a balanced chromosomal structure and may offer a greater likelihood of achieving a successful pregnancy.

When Is Preimplantation Genetic Testing Recommended?

The decision to perform PGT is always based on an individual fertility assessment and personalised medical advice. PGT is particularly recommended in the following situations:

Advanced maternal age, generally from 35 years onwards.

Recurrent miscarriage.

Previous implantation failure during IVF treatment.

Patients with known chromosomal abnormalities.

Risk of transmitting an inherited genetic disorder.

When additional information may help guide embryo selection and treatment planning.

How Is Preimplantation Genetic Testing Performed?

Embryo Development to the Blastocyst Stage: Embryos are cultured in the laboratory until they reach the optimal stage for biopsy, typically on day 5 or day 6 of development.
Embryo Biopsy: Between two and seven cells are carefully removed from the embryo.
The procedure is performed by highly specialised embryologists and is designed to preserve the embryo’s developmental potential.
Embryo Vitrification: Following biopsy, the embryo is vitrified and safely stored while awaiting the results of the genetic analysis.
Genetic Analysis: The biopsied cells are analysed in a specialised genetics laboratory to identify potential chromosomal abnormalities or inherited genetic conditions.
Embryo Selection and Transfer: Once the results are available, embryos that have not been found to carry the genetic abnormalities being investigated. This personalised approach helps optimise treatment planning and improve reproductive outcomes.

Frequently Asked Questions About Preimplantation Genetic Testing (PGT)

Can PGT Be Performed in Any IVF Treatment?

PGT can only be performed during IVF treatment and when embryos successfully reach the blastocyst stage.
Not every IVF cycle requires PGT.
Your fertility specialist will assess whether genetic testing is appropriate based on your medical history, fertility diagnosis, and reproductive goals.

Does PGT Replace Other Prenatal Tests?

No. Preimplantation Genetic Testing helps reduce genetic risk before pregnancy begins, but it does not replace standard prenatal screening or diagnostic tests performed during pregnancy.
For this reason, once pregnancy has been confirmed, routine prenatal testing is still recommended.
This is particularly important because, in some cases, mosaicism may occur—a situation in which both normal and abnormal cells coexist within the same embryo.

Is Preimplantation Genetic Testing Safe?

Yes. PGT is a well-established and widely used technique in assisted reproduction. When performed by experienced embryology teams and at the appropriate stage of embryo development, it is considered a safe and reliable procedure.

Request Your Appointment with No Obligation

At GAIA Fertility, we approach Preimplantation Genetic Testing with scientific rigour, clinical expertise, and complete transparency.
Because the most important fertility decisions deserve to be made with clarity, confidence, and the support of a team you can trust.