You probably know that IVF treatment is not always successful the first time. But what happens if the second, third and fourth attempts don't result in a happy baby? Firstly, you will have to go through a series of tests, which you can read about in many other blog articles on this website. On the other hand, work is being done to add more procedures to IVF in order to optimise treatment. For example, embryos are usually examined more closely before they are implanted in order to detect abnormalities at an earlier stage. The aim is to ensure that only healthy embryos are transferred. Of course, this does not guarantee pregnancy, but it does increase the chances. Preimplantation genetic diagnosis of aneuploidy, or PGT-A for short, is one such additional test.

What should be investigated?

There are many reasons why an embryo does not implant in the uterine lining as it should. This can be due to illness in the mother or father, poor timing or even the embryo itself. The latter can be detected with PGT-A. The embryo is to be screened for aneuploidy, but what is aneuploidy?

Every human being is made up of countless individual cells that all carry the same genetic material in their nucleus. This genetic material is called DNA. It is a code that is coiled into a chain called a chromosome. Every human being has 46 chromosomes. They are not all different, but form pairs, so there are actually only 23 different chromosomes, but they are all duplicated. This is because both the egg and the sperm only have half a set of chromosomes. So the child gets chromosomes 1 - 23 from the mother and chromosomes 1 - 23 from the father. This gives the child another 23 pairs of chromosomes, making a total of 46 chromosomes. The last pair of chromosomes, number 23, represents the sex hormones, i.e. X and X in females and X and Y in males.

A set of 46 chromosomes is called euploid, which means normal or normal number. Aneuploidy is therefore a condition in which there are more or fewer chromosomes than normal. In most cases, the resulting defects are so severe that the embryo is not viable and either fails to implant or is rejected by the mother's body. The latter results in miscarriage.

A few aneuploid conditions are viable, but still have a lower chance of implantation and an increased risk of miscarriage.

What diseases can you reduce the risk of?

PGT-A can also be used to detect and sort out embryos with the above conditions. The best known of these conditions is trisomy 21, also known as Down's syndrome. In this condition, affected individuals have three instead of two chromosomes 21. People with this condition are usually very viable with a little help and usually live to an old age. There are two other forms of trisomy, Pätau syndrome (trisomy 13) and Edwards syndrome (trisomy 18). In both cases, 90% of children die before birth and few live beyond the age of 5. The sex chromosomes are the least affected. There are various combinations, including X0 (Turner syndrome), XXY (Klinefelter syndrome) and XXX (trisomy X). People with these conditions usually need hormone therapy to improve the maturation and function of their sex organs, but otherwise they are very healthy.

Treatment procedure

Now that you know what PGT-A involves, you may be wondering what exactly will be done. For you as a patient, very little changes compared to normal IVF. The only difference is that the time between egg collection and embryo transfer is longer.

As with normal IVF, you will receive stimulation treatment beforehand so that the follicles containing the eggs in your ovaries can mature optimally. Shortly before ovulation, several eggs are retrieved by puncture and fertilised in a test tube with your partner's sperm. When the embryos have a sufficient number of cells, a few cells are taken as biopsies with a very fine needle. These are then sent to a laboratory where they are examined for abnormalities in the number of chromosomes. It takes a few days or weeks for the results to come back, depending on the tests that are done. After NGS (Next Generation Sequencing), where all the chromosomes are examined, the embryos are cryogenically frozen and then thawed before implantation.

Once the chromosome set has been examined, the sex chromosomes are of course also determined, so that the sex of the embryo can be determined in addition to its health.

Who should PGT-A be used for in healthcare settings?

If you have not had IVF before, it is recommended that you try it first without further tests. This is only recommended for high-risk groups. These include couples where one or both partners have already been tested for chromosome abnormalities. Women with more than two failed IVF attempts are also in this group. Women over 35 are also generally considered to be at risk of pregnancy and may benefit from such screening.

But be aware that these recommendations have not been made by ethics committees or similar bodies, only by the clinics themselves.

Where is PGT-A allowed?

Because it is ethically very critical to classify an embryo as better or worse, as worthy of life or not, based on possible diseases or its sex, such prenatal diagnostic methods are banned in many European countries.

So if you want these treatments, you have to travel. Fertility clinics in Europe advertise PGT-A and other services. When planning your trip, you should bear in mind that IVF can take several weeks, including the additional tests. Of course, there are additional costs involved. The best way to find out exactly how you should plan your trip is to discuss this with the clinic of your choice during your initial consultation.

As with almost everything in prenatal diagnostics, there are two sides to the coin. Using PGT-A in combination with IVF can increase the chances of pregnancy and the chances of having a healthy child. However, the ethical conflict is not small. It is up to you to decide where you stand on this issue, and you can legally seek treatment in another country. Of course, PGT-A does not guarantee a successful pregnancy or a healthy baby.