Preimplantation Genetic Testing for Aneuploidies (PGT-A)
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PGT-A

Preimplantation genetic testing for aneuploidies is a process designed to identify the embryos most likely to result in the birth of a healthy baby. This is achieved by assessing the embryo’s genetic material. Formerly, PGT-A was known as preimplantation genetic screening (PGS).

Why is the genetic material tested?

Each one of us has a genetic blueprint — an ‘instruction manual’ that makes us uniquely human and determines our individual characteristics. This blueprint is contained in every cell of our bodies and is packaged into structures called chromosomes. Normally, there are 46 chromosomes — 23 are inherited from the mother and 23 are inherited from the father.

During conception, chromosomes from the mother and father may combine incorrectly, resulting in an abnormal number of chromosomes in the embryo. In most circumstances, an abnormal number of chromosomes is incompatible with life. If these abnormal embryos are transferred, they fail to implant successfully or miscarry. However, some abnormal embryos can carry through to birth and result in a baby with a chromosomal disorder — the most well-known one is Down Syndrome.

How does PGT-A work?

PGT-A involves taking a biopsy of the embryo after it has grown and developed for 5–6 days. We take 5–7 cells from its outer layer that would otherwise be destined to form the placenta. From this sample, we can predict the number of chromosomes present in each cell, allowing us to determine whether the embryo is likely to be normal or abnormal. This information guides our decision on the best embryos to transfer, which helps prevent the transfer of embryos that may result in unsuccessful transfer, miscarriages, or babies with chromosomal abnormalities.

What percentage of embryos have abnormal chromosomes on Day 5?

The percentage of embryos with abnormal chromosomes on Day 5 increases with maternal age.

What are the risks of PGT-A?

At first glance, conducting PGT-A on every embryo may seem beneficial. However, there are a few limitations that prevent its non-selective use:

Risk of harm to the embryo

Embryos are fragile, so any procedure that involves handling the embryo and disturbing its surrounding conditions poses the risk of harm. However, while the risk of harm will always exist, it is thought that the overall risk of damage to the embryo is minimal. The level of risk is also related to how well the biopsy is conducted, which is why we have experienced and skilled scientists on hand to perform these procedures.

Non-indicative sample

When we conduct testing on a sample of cells from the embryo, we are assuming that this sample is representative of all the cells in the embryo. However, this may not be true – a condition called mosaicism may exist, where some of the embryo’s cells have an abnormal number of chromosomes and some have a normal number. Embryos displaying mosaicism can still result in a healthy, live birth. Therefore, the test may cause us to discard embryos that have the potential for a successful, ongoing pregnancy. To help avoid this, we also assess the level of mosaicism in the embryo. This gives patients the option of still proceeding with a transfer if the embryo only displays a low level of mosaicism. On the other side of the coin, a normal PGT-A also does not guarantee that the embryo has a normal number of chromosomes. In the setting of a normal test result, we still recommend patients undergo antenatal screening.

Indeterminate results

The results of the genetic testing may return as ‘indeterminant’, meaning the test could not determine whether the genetic material of the embryo was normal, or abnormal. This may occur for a variety of reasons, including a poor-quality embryo.

Who do we recommend PGT-A for?

We generally recommend PGT-A for certain groups of people, including those who:

  • Have a history of recurrent miscarriages
  • Have a history of repeated unsuccessful IVF cycles
  • Have a family history of chromosomal disorders
  • Have had a previous Down syndrome affected pregnancy
  • Are of older maternal age (>37 years).

Your Newlife fertility specialist will take the time to understand your personal situation and preferences, before helping you to decide if PGT is right for you.

What is the cost of PGT-A?

At Newlife IVF, preimplantation genetic testing currently costs $780 per embryo.* Please visit our fees page for more information.

*Fee correct as of 1 January 2024.

Frequently asked questions

  • What is PGT?

    Preimplantation genetic testing (PGT) is a broad term for a range of scientific techniques available during IVF to identify genetic abnormalities in embryos before they are transferred into the uterus.

    PGT may be requested by couples or individuals who are at risk of passing on a genetic condition or structural chromosome rearrangement to their offspring. PGT may also be used to assess the number of chromosomes in an embryo.

  • What is PGT-A?

    PGT-A is a genetic test designed to check the number of chromosomes in your embryo. An incorrect number of chromosomes is called chromosome aneuploidy, which can increase the chance of miscarriage or the birth of a baby with a chromosome abnormality.

    PGT-A provides information to help select the best embryo for transfer into the uterus and improve your chances of a successful pregnancy.

  • How accurate is PGT-A?

    Current PGT-A techniques are highly accurate (greater than 97%). However, PGT-A is still considered a screening test. This means false positives and false negatives can occur.

  • How is PGT-A performed?

    Once an embryo (created as part of an IVF cycle) has reached the blastocyst stage (usually after 5–6 days of growth), a few cells are removed from the embryo. The cells obtained are then analysed using the PGT-A technique. Based on the results, your genetic counsellor and fertility specialist can advise which embryos are suitable to transfer into your uterus.

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Get in touch

For more information or to book an appointment with one of our fertility doctors, please call (03) 8080 8933 or email [email protected]. Fertility appointments can also be booked via our online booking page.

Our three Melbourne clinics are based in Box Hill, Clayton and East Melbourne and are open Monday–Friday: 8:00am–5:00pm. We welcome patients from all over Victoria, as well as those seeking care interstate or internationally. All fertility treatment requiring day surgery or lab access (e.g. egg collection, embryo transfer) will take place at our state-of-the-art treatment centre in Box Hill. Fertility consultations and IVF cycle monitoring can be arranged at all three Melbourne clinics.

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