Testing Embryos Before Transfer
When undergoing in vitro fertilization (IVF), women have more options than ever before to ensure a healthy baby. Preimplantation genetic testing (PGT) is a type of genetic test that can be performed on the embryo prior to transfer to look for any chromosomal abnormalities and other genetic conditions. With PGT, fertility patients can select the best embryo to transfer.
Let’s start with carrier screening
Many prospective parents will consider carrier screening before deciding to start a family. This test looks for certain genes that can be passed down to a baby. Cystic fibrosis (CF), sickle cell disease, and spinal muscular atrophy (SMA) are just a few examples of diseases that can be screened for. Most carrier screens look for recessive disorders, which means that both mom and dad must carry the same gene for the baby to be at risk of inheritance. If both parents carry the gene, there is a 25% chance the baby will have the disorder. With this in mind, many couples move on to PGT to determine which embryos are not at risk.
Understanding PGT
Preimplantation genetic testing must be done in conjunction with IVF. With IVF, the woman will typically be given medication to stimulate the development of multiple eggs in the ovaries. The eggs are then retrieved and combined with sperm in a lab to create embryos. Starting on Day 3, a single cell can be taken from the rapidly dividing embryo for PGT testing. The biopsy does not harm the future baby but can provide patients with a wealth of information.
Understanding results
There are a few different types of PGT that can be performed. Regular PGT screens for chromosomal abnormalities, such as Down syndrome. Some chromosomal abnormalities are compatible with life, but some are not, and many are associated with an increased risk of miscarriage. Most patients undergoing IVF want to do everything possible to ensure the highest chances of success, so transferring a chromosomally normal embryo is preferred, but each case is unique. A different version of the PGT test, known as PGT-M, can screen for monogenic disorders. With PGT-M, couples with a positive carrier screen will know which embryos are affected by the inherited genetic disorder and which embryos are healthy.
Test to transfer with confidence
In vitro fertilization isn’t perfect, and a baby is never guaranteed, but with the addition of certain tests, the chances of a healthy baby can increase significantly. For couples who carry the same gene, PGT-M is a game changer that can help identify which embryos are affected by the condition. For other patients who may want to avoid a chromosomal abnormality, regular PGT is a great add-on. Regardless of the reason, the PGT test provides helpful information about the health of the embryos so couples can go into the IVF process feeling confident.
