PGT-A: New hope for women who have had to delay having a child until later ages

For women who have had to delay marriage or having kids because of their education or career plans, preimplantation genetic testing (PGT-A) is becoming a hope.

Why is it harder to conceive and the risk of having a baby with anomaly increases as the woman gets older?

As women get older, the time taken to conceive is getting longer, and the risk of pregnancy to result in miscarriage increases. This situation is usually due to the increased incidence of abnormalities such as chromosomal deficiencies or excesses in the eggs produced as age progresses. This makes it difficult to get pregnant, and also increases the risk of miscarriage in pregnancy or the risk of having a baby with anomaly. While the probability of chromosomal problems in the resulting embryos is 20-25% in women aged 26-29, this rate rises to 80-90% for 44-45 years old.

In virtue of the PGT-A method, the blastocyst stage embryos (which has reached the 5th or 6th day) obtained by performing in vitro fertilization (IVF) are biopsied from the part that will form the embryo’s  trophectoderm layer, the embryos are frozen and stored.

The cell samples collected are sent to the genetic laboratory and all chromosomes, which are our building blocks, (22 pairs of somatic and additionally X and Y sex chromosomes) are screened. According to the PGT-A result, in case there is an embryo that is evaluated as chromosomally normal, the transfer of the healthy embryo is performed with the freeze-thaw procedure.

It is very clear that chromosomal problems can be detected even in embryos that are considered to be of very high quality in the laboratory. In other words, the fact that the embryo is very beautiful in shape is not a sign of to be a chromosomally healthy embryo. Thus, as the age of woman who is performed by IVF  increases, the chance of getting pregnant decreases despite good quality embryo transfer and the risk of losing pregnancy with miscarriage or having a baby with anomaly increases.

If an embryo having of a healthy chromosome sequence is detected with PGT-A, age of the female is not important anymore even with a single embryo transfer, and a pregnancy chance of 70-74% can be obtained regardless of age. Meanwhile, the risk of miscarriage that is normally goes up with the woman age, diminishes in pregnancies obtained by PGT-A method, because the risk of miscarriage increases mostly due to chromosomal anomalies. While the risk of loss is around 40% for the pregnancies acquired after the age of 38, this rate rises to 60-70% in the 43-44 age group. However, in pregnancies obtained by PGT-A method, the risk of miscarriage decreases to 8-10% in all age groups.

Ultimately, live birth rates remain around 55-60% even for the women in the 42-45 age range.

In the past, biopsy was performed on the 3rd day for this purpose, but in recent years, it is now done on the 5th or 6th day, that is, at the blastocyst stage. The advantages of performing a biopsy at the blastocyst stage are as follows;

  1. While the 3rd day embryo has 7 to 8 cells in an ideal state, it reaches 250 cells at the blastocyst stage, and the inner cell mass that will form the baby and the outer cell layer that will form the baby’s mate (trophectoderm) are differentiated. Therefore, while 3rd day biopsy allows collection of a single cell, 3-5 cells can be taken from the outer cell layer without touching the inner cell layer that will form the baby in the biopsy at the blastocyst stage. This method make sampling to be taken from a smaller volumetric part of the embryo and examination can be performed from 3-5 cell samples instead of one.
  2. A biopsy performed on the 3rd day allows examination of only certain chromosomes, however, all chromosomes can be evaluated by performing a biopsy at the blastocyst stage.
  3. There are studies showing that the probability of pregnancy by transfer after the 3rd day biopsy is less than the embryos without biopsy, however, biopsy at the blastocyst stage does not have any negative effect on the adherence of the embryo.

Thus, with PGT-A Method;

  • After the age of 38 (between 38-45 years), the pregnancy chances rise to 70-74% with a single healthy embryo transfer,
  • The risk of losing the resulting pregnancy by miscarriage decreases to 8-10%,
  • Multiple pregnancy and pregnancy with anomalies are avoided.

In conclusion, we recommend PGT-A method in addition to IVF treatment in our female patients whose age is 38 years and older. The PGT-A method can also be applied in couples having recurrent pregnancy loss or recurrent IVF failure, although its effectiveness is controversial.

 

Contact information :

Author : Prof. Dr. Mehtap Polat
Telephone : +90 530 011 41 33
E-mail : info@mehtappolat.com