Understanding Preimplantation Genetic Testing (PGT): Euploid vs. Aneuploid Embryos and Their Impact on IVF Success
Preimplantation genetic testing (PGT) has transformed the field of in vitro fertilization (IVF), giving patients a better chance at achieving a successful pregnancy. By analyzing embryos for chromosomal abnormalities before implantation, PGT helps doctors select the healthiest embryos, thereby increasing implantation rates, reducing miscarriage risks, and improving overall IVF success. A crucial part of this process is distinguishing between euploid and aneuploid embryos, as their chromosomal makeup plays a significant role in the outcome of an IVF cycle.
What is Preimplantation Genetic Testing (PGT)?
PGT is an advanced screening technique used during IVF to examine the genetic composition of embryos before they are transferred into the uterus. The test involves taking a small biopsy from the embryo (typically on day 5 or 6 of development) and analyzing the DNA for chromosomal abnormalities. The goal is to identify embryos that have the best chance of implanting and developing into a healthy baby.
There are different types of PGT, including:
PGT-A (Aneuploidy screening): Detects embryos with abnormal chromosome numbers.
PGT-M (Monogenic disorders): Screens for specific inherited genetic diseases.
PGT-SR (Structural rearrangements): Identifies embryos with chromosomal structural abnormalities.
Among these, PGT-A is the most commonly used to differentiate between euploid and aneuploid embryos.
Euploid vs. Aneuploid Embryos
A euploid embryo contains the correct number of chromosomes—46 (23 pairs). These embryos are considered genetically normal and have the highest chances of implantation and a successful pregnancy. Euploid embryos are less likely to result in miscarriage or genetic disorders, making them the preferred choice for transfer in IVF cycles.
In contrast, an aneuploid embryo has an abnormal number of chromosomes, which can lead to developmental issues. Some common types of aneuploidy include:
Trisomy: An extra chromosome (e.g., trisomy 21, which causes Down syndrome).
Monosomy: A missing chromosome (e.g., Turner syndrome, where only one X chromosome is present).
Other chromosomal duplications or deletions that prevent normal fetal development.
Most aneuploid embryos fail to implant or result in early miscarriage. Therefore, identifying and avoiding aneuploid embryos can significantly improve IVF success rates. Seriously! Check out this study and see for yourself.
How PGT Impacts IVF Success
PGT plays a crucial role in improving IVF outcomes by ensuring only the healthiest embryos are selected for transfer. Some key benefits include:
Higher Implantation Rates – Since euploid embryos are more likely to implant successfully, PGT helps reduce failed transfers.
Lower Risk of Miscarriage – Many miscarriages occur due to chromosomal abnormalities. By transferring only euploid embryos, the risk of pregnancy loss is significantly reduced.
Reduced Need for Multiple IVF Cycles – Selecting chromosomally normal embryos increases the likelihood of pregnancy in fewer cycles, saving time, money, and emotional stress.
Lower Risk of Genetic Disorders – PGT helps prevent chromosomal conditions like Down syndrome, giving parents peace of mind.
While PGT is a powerful tool, it’s not foolproof. Some embryos are classified as mosaic, meaning they have both normal and abnormal cells. In some cases, mosaic embryos can still result in a healthy baby, but careful evaluation is needed.
Don’t take our word for it; check out this study that was conducted in 2019! If you can’t open it, then let us give you the main takeaway. Aneuploid embryos failed almost 100% of the transfers, meaning these embryos have an extremely low probability of success. PGT can help save time by selecting the embryos that can get to live birth.
“When it comes to embryos, you want the best candidate for the job. Euploid embryos are your top performers, and aneuploid embryos are... well, let’s just say, they’re still in the waiting room.”
