At Repromed, we’re relentless in our mission to help you have a baby. That’s why discussion of embryo screening is always a vital part of your fertility consult. Screening for chromosome changes which occur at conception – usually due to an extra or a missing chromosome being present in an egg or sperm – can help reduce the time taken to achieve a live birth.
Typical embryonic cells contain 46 chromosomes in 23 pairs – 23 chromosomes from each parent. If the egg or sperm has an extra or missing chromosome, then there is a high chance of miscarriage or failed implantation. This is the main cause of declining fertility and increased chance of miscarriage with increasing maternal age.
Frequently Asked Questions About PGT-A
PGT-A, or Preimplantation Genetic Testing for Aneuploidy, is a genetic test performed on embryos created through IVF. It screens embryos for missing or extra chromosomes, which are a common cause of miscarriage, failed implantation, and reduced fertility, particularly as maternal age increases.
PGT-A may be recommended if you:
- Have experienced recurrent miscarriage
- Are over the age of 35 and trying to conceive
- Have had repeated unsuccessful IVF cycles
- Have a family history of chromosome-related conditions
- Your fertility specialist and genetic counselling team can advise whether PGT-A is appropriate for your situation.
There are three main types of preimplantation genetic testing:
- PGT-A: Screens embryos for missing or extra chromosomes.
- PGT-SR: Used for patients with a structural rearrangement (translocation) of their chromosomes.
- PGT-M: Used for patients with a known single gene condition.
Embryos are grown to day 5 of development, at which point a few cells are removed from the outer layer of the embryo in a process called embryo biopsy. These cells are sent to the Monash IVF Genetics laboratory for testing, while the embryos are frozen and stored until results are available.
The cells are analysed using next generation sequencing technology. The DNA is amplified into millions of copies and compared to the human genome. Specialised software then identifies whether there are extra or missing chromosome fragments, which indicates aneuploidy.
If you are undergoing Pre-Implantation Genetic Testing (as agreed with your treating clinician), the Embryology team will provide timelines for your results when they update you on the biopsy. Once results are available, your fertility specialist will review them with you and advise which embryos are most suitable for transfer. Embryos with the correct number of chromosomes offer the highest chance of implantation and a successful pregnancy.
While testing is performed, embryos remain frozen and safely stored. Once results are available, embryos with the highest chance of implantation are transferred individually in a frozen IVF cycle. Any remaining viable embryos can stay frozen for future use.
While we perform the genetic testing, your embryos are kept frozen and in storage. When we identify embryos with the highest chance of implantation, they’re transferred individually in a frozen IVF cycle. Your remaining viable embryos stay frozen for future use.