What is pre-implantation genetic testing?
During the IVF (In Vitro Fertilization) process your fertility doctor will be fertilizing the eggs and then growing those eggs into embryos, generally until day five of development. After this 5-day mark, the fertility doctor will perform a biopsy on the embryo and send off the cells to the genetics lab for genetic testing. This is when PGT is performed.
All genetically normal humans have 46 chromosomes, 23 pairs. Half of the pairs are from the egg and the other half are from the sperm. In order for it to be a normal pregnancy the embryo must have a normal number of chromosomes. Pre-implantation genetic testing looks at those chromosomes to see how many copies the embryo has of each. A normal readout would be 46 XX resulting in a normal female embryo or 46 XY resulting in a normal male embryo.
At this time of genetic testing, if there are any genetic abnormalities in the embryo the PGT test will show us that. The abnormality would be either missing or extra chromosomes. If this is the case that embryo is not eligible to be transferred because it would not lead to a pregnancy or could lead to a miscarriage.