In the past few years, the technology for preimplantation genetic testing of embryos (now referred to as the acronym PGT) has improved by leaps and bounds. PGT is now a very reliable tool for understanding the genetic competence of embryos before they are transferred into the womb. Some providers recommend testing all embryos and others have been hesitant to embrace this approach.
Today, we will discuss the pros and cons of IVF genetic testing. Each woman’s situation and clinic mindset can be different, so it’s important to know where the facts that their decisions are based on.
What Is PGT?
You may not be familiar with the term of PGT. That’s because, not long ago, PGT was known as PGS (preimplantation genetic screening) or PGD (preimplantation genetic diagnosis). PGS and PGD are two different types of genetic testing.
PGS (Preimplantation genetic screening) tests an embryo for the correct number of chromosomes. If an embryo does not have the correct number of chromosomes, it is referred to as aneuploidy.
PGD (Preimplantation genetic diagnosis) was another type of genetic screening which detects the presence of genes for specific diseases.
The terms were changed recently following a meeting at the World Health Organization by a large multinational group of experts, including Dr. Joseph Davis, the founder of this website (Destination Fertility).
The goal of the change was to standardise the terms across groups of people working in fertility care globally and to make them more accurate. PGS was changed to PGT-a, where “a” stands for aneuploidy, or an abnormal number of genes.
PGD is now called PGT-m. The M is for monogenomic (or single gene) disease. Your doctor may use the old or new terms as the change was recent, but no matter what it’s called, the question still remains – should I perform genetic testing on my embryos?
The Pros Of IVF Genetic Testing
There are several reasons to genetically test your embryos.
- You are able to identify your best embryos when there are several to choose from
- The number of eggs a woman has retrieved varies and can occasionally result in a large number of embryos. The best embryos to transfer can be chosen based on the appearance or the rate of growth. Genetic testing can further help choose a highly competent embryo and allow for a single embryo transfer while maintaining a high chance of implantation.
- Reduce the chances of a genetically abnormal embryo
- As women age the number of genetically competent embryos lowers. This can result in lower pregnancy rates, more miscarriages, and an increased risk of having a baby with a chromosomal issue. PGT doesn’t eliminate these concerns, but it can improve the odds of success.
- Consistent unexplained infertility
- Unexplained infertility occurs in approximately 15% of patients trying for a baby. The cause may be identified when you test your embryos. For those women, the number of genetically competent embryos may be fewer than expected for your age, and testing can help find the embryo with the highest chance of pregnancy.
- Avoid passing on a particular genetic condition
- PGT can be used to identify the total number of chromosomes and their location, called PGT-a (where “a” stands for aneuploidy, or “abnormal-chromosome status”) or to identify a particular abnormal gene, called PGT-m (where “m” means “monosomy” or “monogenomic”). If you have a genetic condition you don’t want to pass on to your child, PGT-m can be used to eliminate this genetic problem for the next generation of your family.
The Cons To IVF Genetic Testing
There are several reasons and situations where you may elect not to perform genetic testing on your embryos.
- When you only have a few embryos
- The number of embryos recommended for transfer depends on the odds of success. This is often related to your age when the eggs were retrieved. If you are over the age of 35, your doctor may suggest transferring 2-3 or even more embryos at once. If you have a limited number of embryos available, testing may not add anything other than cost and time.
- If you have young eggs
- Eggs collected from women in their twenties and early thirties generally result in high numbers of genetically competent embryos. In this situation, odds are good if you chose an embryo based on the physical characteristics (morphology) you will likely have a genetically competent embryo.
- Testing may not add any benefit
- If your reason for undergoing IVF is blocked fallopian tubes and you have had previous pregnancies, PGT may not help increase your odds of success. Similarly, if you are doing IVF to prevent transmitting HIV or Hepatitis and you are otherwise able to get pregnant, you may consider not testing the embryos as infections would not increase the odds of having a chromosomal abnormality.
- Cost is a major concern
- IVF can be very expensive and PGT is an additional expense. PGT is also not a perfect method. If you are looking to reduce the cost of an IVF cycle and you have had a frank discussion with your doctor about the pros and cons of genetic testing, you could consider not testing the embryos. This is not only cheaper, but could mean moving onto a transfer and hopefully pregnancy faster than if you had to wait for the results.
Choosing to perform genetic testing on embryos is a highly personal decision that should be made between you and your physician. Knowing all of the information will allow you to make the best and most educated decision.
If you are still struggling with understanding if genetic testing is right for your particular situation, consider a free consult with Dr. Joseph Davis to better understand the pros and cons of IVF genetic testing.
Dr. Joseph Davis
Founder of Destination Fertility