On average 60-70% of human embryos (after or without IVF) carry a variety of chromosomal abnormalities. They can arise spontaneously in the cells of an embryo during early stages of its fragmentation or be inherited by the embryo from the parents.
Such anomalies lead to impaired implantation, missed miscarriage, spontaneous abortion, or occurrence of congenital defects. The most common disorders are the ones associated with a change in the number or structure of chromosomes (aneuploidy).
What is aneuploidy? Aneuploidy is a term used to describe a difference in the number of chromosomes. If an egg or sperm is missing a chromosome or has an extra chromosome, this results in an embryo with an extra or missing chromosome, resulting in aneuploidy. The most commonly known example of aneuploidy is Down syndrome which is caused by an extra copy of chromosome 21.
In order to prevent transfer of an embryo with such disorders, the Clinic conducts a study of the chromosomal composition of embryos before their transfer to the uterus of a woman — preimplantation genetic diagnosis (PGD).
To do this, a biopsy of embryos is made (at the blastocyst stage of 5-7 days after fertilization) for testing. Special tools allow retrieving just a few cells from the future envelopes of the embryo. Cells of the embryo itself remain inviolable, therefore it is completely safe for the future baby. After the biopsy each embryo must be vitrified on a separate carrier.
The obtained cells are examined with the help of special equipment. The Clinic uses the most innovative kind of genetic analysis — PGT-A by NGS (Next Generation Sequencing). Today this is the fastest and most sensitive method of analysis that covers the entire genome.
According to the results of the study, in the next cycle only those embryos that do not contain chromosomal abnormalities can be selectively thawed and transferred to the uterine cavity. In addition, PGD is the only way to determine the sex of the unborn baby before the embryo implantation.
Benefits of PGD:
- reduced miscarriage rates;
- higher pregnancy rates per transfer;
- fewer cycles of IVF treatment before success (lower costs and time expenditures);
- greater chances of having a healthy child;
- fewer wasted transfers (implantation failures).
Preimplantation Genetic Diagnosis helps to prevent birth of a child with chromosomal diseases, moreover the risk of miscarriage decreases twice. At the same time, the probability of successful implantation increases by approximately 10%, and the chances of a successful child birth grow by 20%.