Gynecology, Obstetrics and IVF Specialist Op.Dr.Numan Bayazıt gave important information about the subject. Genetic analysis in IVF applications is one of the most important developments in this field in recent years. Couples think that when genetic analysis is done on the embryo, they will give birth to a completely healthy baby. Is this true?
No. It would be possible if congenital anomalies were caused by a single cause, but there are many different causes and it is not possible to detect all of them at the same time. There are also anomalies that are not based on genetic causes.
So, what do we need to understand when we say genetic analysis in IVF?
The best way to explain this is to divide the couples into those with genetic problems and those without. The practices we hear in the media as “increasing success in IVF” are actually about couples who do not have any genetic problems.
Why is genetic analysis performed for the couple who do not have any genetic problems?
To increase the possibility of pregnancy or to help couples who cannot conceive despite repeated IVF applications. So it's not a routine practice. The frequency of application also varies greatly from country to country. While it is used freely in the United States, which many do, in France it can only be done with the permission of the relevant board if there is a genetic disease in the family. It's the same in England. On the other hand, Italy banned it completely for non-medical reasons, because it is a Catholic country. It was forbidden even if the baby to be born was sick. Later, this ban was lifted with a court decision, now it can be done if there is a known disease in the family.
There is no restriction other than gender selection in our country.
I will ask how you increase the success in IVF, but first, can you give a brief information about the diseases that must be done?
As you know, some families have diseases that are passed on from generation to generation. Some are dominant. If the mother or father is sick, the baby will be born sick with a 50% probability. Some are recessive, which is common in consanguineous marriages. Both parents must be carriers for the baby to be sick. For example, Thalassemia, which is frequently seen in our country, and SMA, which we have started to hear frequently because of new treatment methods, are these types of diseases. These families can give birth to a baby who does not have these diseases in the family by applying for IVF.
How do genetic applications increase success in IVF?
The most common reason for not getting pregnant every month in normal life or in vitro fertilization is that not every embryo has a normal chromosome structure. This is actually a different situation from gene diseases that are passed from generation to generation. It means that the 46 chromosomes we have are not normal in number and sequence. It is especially related to the age of the woman because as the woman gets older, the chromosome structure of the eggs deteriorates. While the probability of a good quality embryo to attach at a young age is around 40%, it decreases with age. For example, at the age of 42, one of every 7-8 eggs is intact. However, if we can show that the chromosomes are normal by performing PGT-A before transferring the embryo, the probability of attachment increases to 70%.
So it doesn't guarantee conception?
No, it is not guaranteed. However, for a woman at an advanced age, it at least prevents an unnecessary transfer. It also halves the chances of experiencing a miscarriage. It certainly shortens the time to reach a healthy pregnancy.
So why isn't it used more often?
Because it causes us to lose some embryos. If there are plenty of embryos, this is acceptable. However, if you have a small number of embryos, you may not want to risk losing them. There are 2 reasons for losing an embryo. The first is the biopsy procedure. As a result, a piece of the embryo is taken. With a good embryologist, we can say that this risk is very low. The second is that the result from the laboratory does not reflect the truth. It's just a matter of technical reasons. In fact, it sometimes happens that the transferred embryos with abnormal chromosome structure result in a healthy birth.
As a result, PGT-A is a decision that should be taken after discussing all the details with the couple, according to the characteristics of the couple. If there is an abnormality in the karyotype analysis of the couple, it should definitely be done. I recommend it to prevent many unnecessary transfers and miscarriages in women with abundant embryos at advanced age. It should be recommended in those with few embryos at advanced age, if there is a risk of disappointment after unsuccessful transfers and abandoning the trials. If women whose ovaries are at risk with surgery or various treatments want to store embryos for the future, it makes much more sense to keep the ones that have been proven to be healthy after PGT-A. Even if there is not enough scientific evidence for those who have had repeated IVF attempts, I recommend it to at least understand what is going on.