Preimplantation Genetic Testing (PGT)

What Is Preimplantation Genetic Testing?

Preimplantation genetic testing (PGT) is a diagnostic screening in which our embryologists check embryos at the cellular level. By analyzing embryos at the cellular level, we can uncover abnormalities related to the number of or the rearrangement of chromosomes, which can cause Down syndrome in the child or early pregnancy loss.

Additionally, the embryologist can check abnormal genetic arrangements that can cause diseases such as sickle cell anemia or cystic fibrosis.

PGT for Chromosomal & Genetic Abnormalities

To test for chromosomal or genetic abnormalities, there are three forms of preimplantation testing:

• Preimplantation genetic testing for aneuploidy (PGT-A)
• Pre-implantation genetic testing for monogenic disorders (PGT-M)
• Pre-implantation genetic testing for chromosomal structural rearrangements (PGT-SR)

Am I a Candidate for PGT Testing?

Genetic testing should be considered for the following patients:

• Women who are aged 35 or older
• Carriers of dominant or recessive genes for known inherited disorders
• Experience unexplained infertility
• Have had repeated unsuccessful infertility treatments
• Have had recurrent miscarriages
• Those who already have frozen embryos and want to test them for future transfer success

Genetic Carrier Screening

When Is PGT Testing Performed?

An embryologist performs the biopsy to retrieve cells for PGT when the embryo reaches the blastocyst stage, usually by day 5 or 6 of embryo development. The embryologist biopsies (removes) 5-10 cells from the trophectoderm of the embryo, which is the part of the embryo that becomes the placenta. The embryo is then cryopreserved, and the biopsied cells are sent to the PGT laboratory where their DNA is amplified and tested.

PGT Testing Risks

There are a few things to consider when deciding about preimplantation genetic testing:

• PGT is a screening test, not a diagnostic test. That means it is not 100% accurate and there’s still a small chance of implanting an embryo with a chromosomal abnormality.
• The biopsy, freezing, and thawing of embryos can result in damage to a small percentage of tested embryos, which are then not able to be used for implantation.
• Some studies suggest that the biopsy may lower the implantation ability of some embryos, even if the chromosomes are normal. This effect may be more pronounced in younger patients.
• Even after having PGT, a pregnant woman may still want to consider getting certain prenatal blood tests to check on the baby’s genetic health.

Why Should I Consider PGT Testing?

Our fertility specialists recommend PGT for some couples because research shows genetic abnormalities can be a cause of infertility or recurrent pregnancy loss.

There are several additional benefits to undergoing PGT testing during IVF, which our specialists will review with you in depth.

Recurrent Pregnancy Loss

Increases the Likelihood of Transferring Genetically Normal Embryos

More than 50% of miscarriages are caused by abnormal chromosomal conditions.¹ Genetic testing of embryos is a proven way to increase the chances of IVF success for many patients. One reason is that more than half of miscarriages are caused by abnormal chromosomal conditions. Transferring embryos whose chromosome numbers have been checked may improve the chances for a stable ongoing pregnancy and minimize the risk of early pregnancy loss.

Improves the Chance of Pregnancy Success for Women 35 and Older

PGT testing can help women over 35 conceive. The risk of trisomy, a chromosomal condition characterized by one additional chromosome, rises to more than 30% for women in their 40s.²

Studies show that as a woman ages, eggs that are being matured for retrieval or ovulation are more likely to end up with the wrong number of chromosomes. Once fertilized, these eggs are more likely to divide chaotically. The end result is an embryo that has abnormal chromosome numbers.

Lowers Risk of a Multiples Pregnancy

PGT minimizes some of the risks associated with multiples pregnancy (twins or more). The test identifies the healthiest embryos for implantation, often enabling doctors and the family to transfer only one embryo, which greatly reduces the chance of multiples. A multiples pregnancy can pose increased health risks to both the mother and the babies.

Reveals the Gender of the Embryo

As a result of PGT, intended parents may also know the sex of the embryo, if they so choose. The Fertility Institute does not do testing exclusively for gender selection.