Whether to PGT-A test your embryos or not is a decision to make with IVF. It can be overwhelming when you have to add this question to your already long list of decisions. Does it feel never ending sometimes, all these decisions? You’re not alone in that thinking. But having the key considerations laid out below will hopefully save you time and free you up to have those moments of joy that seem rare when you’re struggling to get and stay pregnant. That’s my hope for you.
What is PGT-A in a nutshell?
PGT-A is short for Preimplantation Genetic Testing for Aneuploidy. It’s an optional test done after embryos reach a point (called the blastocyst phase) and about 10 cells extracted from the embryo and sent off to a lab for analysis. The cells are the part that form the placenta, not the baby. Then you wait one to three weeks approximately, but that depends on the clinic and if the test is done on site or sent to another lab.
Your results will tell you whether your embryo is or embryos are abnormal (the technical term is aneuploid) or normal (euploid) or other that classification such as mosaic. Everyone’s rooting for normals but many babies have been born from mosaic embryos. Read more on this in part 2. The embryologist involved with your case would then use this process to choose the best looking and classified embryo for your frozen embryo transfer (FET) the following month or a future month.
The older term is PGT-S or CCS. There are a couple of others such as PGT-M but it is only done when you know the egg and sperm carrier(s) is a known to have a reason to test. I’ll just be talking about PGT-A testing here.
Why would I do PGT-A on my embryo?
This process in theory find which embryos will give you the best chance of a live birth and for a baby with 46 chromosomes. Abnormals are usually discarded and many clinics will not transfer an abnormal embryo. There is controversy over this but the theory was that any abnormal embryo would eventually lead to a miscarriage because the number of chromosomes isn’t correct, but it is more accepted that it is used to increase your chance of a live birth by choosing other embryos.
Here’s the main reason. Individuals or couples choose to do PGT-A testing to get rid of all those abnormals that would give you a significantly increased chance of miscarriage. This claim is debatable and depends on other factors, but that’s the rational why someone would do it. They want to be more certain – but not 100% – that the transfer will lead to a pregnancy.
There’s a lot more to consider when you’re making the decision to test or not. You need to decide what’s right for you – and with your partner if you have one. I’m sharing this with no judgement. These are considerations. Talk to your fertility doctor for medical advice.
Considerations for doing PGT-A or not
Age. The older the person who is supplying the eggs gets, the higher the likelihood of having abnormal or rather aneuploid embryos starting at around age 32-35. PGT-A testing can be a a great option for when the egg supplier is 35 years of age or older. That is because the chances of abnormality increases. At age 36, 56% of embryos are normal, 37% by 40 and about 27% by age 42 on average. This is for Day 5 embryos, approximate and only on average based on this 2016 peer reviewed article.
Time / frozen vs fresh transfer. A fresh transfer isn’t a possibility with PGT-A testing. This means waiting more time to transfer. You need to wait until the results are shipped and the analysis is completed, so the embryos are frozen in the meantime. Some people like having to wait to give their body time to recuperate from the OHSS or everything their body went through before transfer, unless you’re doing reciprocal IVF. Others don’t want to wait. A frozen transfer has a slightly higher success rate than fresh transfer, so frozen versus a fresh transfer is relatively equal. With
Financial cost. It varies but it costs a lot extra for PGT-A. There are various fee structures and packages at different clinics. Some clinics require you to pay upfront regardless of whether you even have any embryos to test. Something to consider is the cost of time, emotional toll and actual cost of doing another FET if a transfer failed. Also consider this together with age of the egg supplier. The cost may also increase because testing inevitably leads to a frozen embryo transfer which is more expensive than a fresh transfer. But think of the cost you’d incur if you have more than one embryo and freeze it anyway (see above). You usually pay for embryo storage by patient, regardless of how many embryos you have. Sometimes you have to do ICSI if you’re going to do PGT-A, and that can sometimes come with an added cost on top of PGT-A, so the fees can really add up.
Data about the euploid rate from PGT-A lab. Requesting this data could provide more guarantee that you’re choosing the best lab to do PGT-A by comparing across labs. If you find your lab’s results aren’t good enough, you might choose not to test or to change clinics.
Concerns that embryos may be discarded that could result in a person with a full life such as Klinefelter syndrome. There are genetic conditions such as this that may be discarded when there is a chance that there is a chance at producing a baby with a quality of life. This is rare.
Concerns that abnormals can resolve themselves. This technology has been available since about 2009. That’s not long and there has been hesitancy by some experts that testing eliminates embryos that may have course corrected or resolved in the uterus over time and ended up as a healthy baby. This has been a legitimate concern, with some recent studies and preliminary studies refuting this claim. Please talk to your genetic counsellor and fertility physician or book a call with me to talk this through.
How many embryos make it to blastocyst phase. If you have 1 to 3 then it may not be worth it to test for some people. Or, you may decide to do another round of an egg retrieval and combine your embryos from those two or more cycles to test your embryos. The number that you decide is few enough not to test is up to you of course. Whereas if you have many, many embryos you may decide to test half or some of them to save money.
Sex selection. This isn’t the only way to find out the sex of your embryos ahead of time but it can be. This is not possible in Canada but it is in the US and many other countries.
The freezing method your clinic uses. The great news is that many clinics will use flash freezing now where the thaw rate is almost 100%. You used to have to worry about losing embryos in a thaw but that’s not the case for many clinics. If your clinic does not use this more modern method, you might consider switching clinics or not testing if you’re staying there in case you lose precious embryos. It’s just a consideration and even without this advancement the percent lost is still low. Talk to your clinic.
Concern there’s an error in the testing. The chance there is an error in the test results is approximately 1 to 5% but talk to your clinic about their known rate of error. This may include concerns of fales positives because only 10 cells are part of the biopsy but doesn’t necessarily mean the rest of the embryo is of that same genetic make-up. It’s rare, but it happens.
Trauma and heartache of a chemical pregnancy, failed transfer or miscarriage. If an abnormal embryo is transferred, then the heartache of the loss is probably a significant consideration. Nobody wishes that for anyone. It adds more trauma to an already stressful experience, but it’s an individual choice of which risks outweigh the other.
History of miscarriage. This is a factor to give a lot of thought to if you’ve genetically tested and identified an abnormality from fetal tissue from a miscarriage. Some people choose IVF after having multiple miscarriages (2 or 3 or more) and having been able to test the fetus and confirm that PGT-A testing would assist in weeding out the embryos with the chromosomal abnormalities. This is an option even if there wasn’t testing done from the pregnancy loss. The most common reason for a miscarriage is chromosomal abnormalities. Please remember that no miscarriage or pregnancy loss is your fault.
Have previously failed IVF cycles. If you’ve had one or more embryos fail to stick or stay that weren’t tested, you might consider testing for a future round.
Other health issues. There are other health issues including the genetic history of the egg and/or sperm that make the decision clear whether testing is the right option. Another reason is a medical or uterine reason to avoid a miscarriage or D&C.
You want more information about your fertility. If you didn’t screen, you’d have less information.
You’d be thinking ‘what if‘. Consider the path of least resistance and think through if you had any issues like a miscarriage that would make you look back and regret not testing. You wouldn’t be able to know if the miscarriage or issue would have been resolved with testing, but if you’d be wondering ‘what if I had‘ and with regret. Factor that into your decision making. Also, if you’re in the unlikely scenario where you only get abnormals, would you wonder ‘what if I hadn’t tested?’. Would you question the research so far and wonder if you should have tried the abnormal embryos.
Have had a previous child with chromosome abnormalities. This depends on many factors. You would talk to your doctor and genetic counsellor about this.
A genetic counsellor’s input. A fertility genetic counsellor is an expert in embryo development. If your clinic has one talk to them. Or you can find one online or from the National Society of Genetic Counselors.
A medical fertility doctor’s input. Input from your reproductive endocrinologist (RE), aka a fertility doctor will be able to provide advice on your specific case. You can always get a second or third opinion from a different doctor or clinic too. Listen to this informative interview with Dr. Tallon from Olive Fertility Centre hosted and housed by Fertility Matters Canada. She talks about age and fertility as it relates to testing at 18:50 minutes and gets more into testing at 21:00. She also goes on to talk about frozen transfer vs. fresh transfer.
If the choice whether to test your embryos is overwhelming and you need more support, book a call and I’ll coach you through it.
References:
Boynukalin, Fazilet Kubra et al. “Impact of elective frozen vs. fresh embryo transfer strategies on cumulative live birth: Do deleterious effects still exist in normal & hyper responders?.” PloS one vol. 15,6 e0234481. 26 Jun. 2020, doi:10.1371/journal.pone.0234481
Dahdouh EM, Balayla J, Garcia-Velasco JA. Comprehensive chromosome screening improves embryo selection: a meta-analysis. Fertil Steril 2015; 104:1503–12
Demko, Zachary P. et al. Effects of maternal age on euploidy rates in a large cohort of embryos analyzed with 24-chromosome single-nucleotide polymorphism–based preimplantation genetic screening Fertility and Sterility. Volume 105, Issue 5, 1307 – 1313
Forman EJ, Hong KH, Ferry KM, Tao X, Taylor D, Levy B, et al. In vitro fertil- ization with single euploid blastocyst transfer: a randomized controlled trial. Fertil Steril 2013;100:100–7.e1
Forman E.J. et al. The nature of aneuploidy with increasing age of the female partner: a review of 15,169 consecutive trophectoderm biopsies evaluated with comprehensive chromosomal screening.Fertil Steril. 2014; 101: 656-663
Munne S. et al. Preimplantation genetic testing for aneuploidy versus morphology as selection criteria for single frozen-thawed embryo transfer in good-prognosis patients: a multicenter randomized clinical trial.Fertil Steril. 2019; 112: 1071-1079
Neal SA. et al. Preimplantation genetic testing for aneuploidy is cost-effective, shortens treatment time, and reduces the risk of failed embryo transfer and clinical miscarriage.Fertil Steril. 2018; 110: 896-904
Tiegs AW. et al. A multicenter, prospective, blinded, nonselection study evaluating the predictive value of an aneuploid diagnosis using a targeted next-generation sequencing–based preimplantation genetic testing for aneuploidy assay and impact of biopsy. Fertil Steril. 2021 ; 115: 627-637
Yang Z. et al. Selection of single blastocysts for fresh transfer via standard morphology assessment alone and with array CGH for good prognosis IVF patients: results from a randomized pilot study.Mol Cytogenet. 2012; 5: 24
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