Embryo Math: Why Aneuploidy Doesn’t Mean a Chromosomal Disorder

Many patients panic when their PGT results show numerous abnormal embryos, fearing that this means they have a high chance of having a baby with a chromosomal disorder. But is that really true? In this episode of Taco Bout Fertility Tuesday, Dr. Mark Amols breaks down the math behind aneuploid embryos, explaining why most won’t lead to a live birth and how natural pregnancy risks remain low. Learn how implantation rates, miscarriage risks, and real-world statistics shape the actual chances of having a child with Down syndrome or other chromosomal conditions. If you’ve ever wondered what your PGT results really mean, this episode is for you!

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Transcript

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Today we talk about embryoth why having abnormal embryos doesn't mean you're at high risk of having a baby with a chromosomal disorder. I'm Dr. Mark Amols and this is Taco about Fertility Tuesday. Today we talk about the difference between having abnormal embryos from PGT and the actual risk of having a child with a chromosomal disorder. Just because you see a lot of abnormal results doesn't mean the odds of having an affected baby are high. In fact, most anapoidia embryos won't even make it to implantation. Let's break down the real numbers and what they mean for your chances of success. So what am I talking about? Well, sometimes when you go through IVF and you get your PGT results back, you end up having a lot of abnormal embryos. And the thing that you start thinking is, if all these embryos are abnormal, does this mean I've been dodging bullets my whole life and I've had a chance of potentially having a baby with down syndrome or some type of other chromosomal abnormality? And the answer is no. And this is because most of the embryos that are abnormal m are never even going to make the implantation. And if they do, they likely are going to end in the miscarriage. Let's talk about a specific sample. Let's say you are 41 to 42 years of age. Your aneemloidy rate would be around 85%, meaning 85% of the eggs are going to be genetically abnormal. Now what's interesting is though, if you look at the chances of having a baby with down syndrome, Even at age 42, your chances are only 1 in 50 that you will have a child with down syndrome. And this is true for pretty much all age groups. For example, if you're under 30 years of age, you know that the unemployed risk is going to be very low. It could even be as low as 20, 25%. But that would scare me if I thought I had a 25% chance of having a child with down syndrome or some chromosomal problem. However, in reality I only have a 1 in 1,000 chance of having a child with down syndrome. And if I look at all cromosomal disorders, not even down syndrome, it'only 1 in 200. Now, just in case you're curious, for the different age groups, the risk of down syndrome is about 1 in 1,000. For people under 30, about 1 in 700. Between about 30 and 35, about 1 in 250. Once you hit about 35 to 37 by 38 to 40 it's about 1 in 141 to 42, about 1 in 50. And when you get to 43 in above, it's about 1 in 25. Matter of fact, even at age 45, about 1 in 10 will have a risk of down syndrome. That means you still have a 90% chance of having a healthy pregnancy. The point is you dont have to be scared about having kids naturally. I run into this all the time. Ill patients be so shocked by having abnormal embryos that they willl say to me is it even safe for us to keep trying on our own? And I have to remind them absolutely. Let's say for example we took 100 embryos that had down syrome. So these are PGT tested embryos. We know they have down syndrome and then we put them into patients. The question is how many of them would actually lead to a live birth? Well, surprisingly only about two of them. So as you can see, the chances are very few will make it there. Even though that sounds very scary putting back those embryos, most will not make it there. There was even a study where they actually went and they had people go through PGT testing and they put back the embryos into everyone. They didn't tell them what the results were. And then after the fact they went back and they unblinded it to find out who ended up getting pregnant, who didn't and what was the quality of those embryos when it comes to anaploy status. And what they found is no one had a live birth with an embryo that came from an employy status from the PGT results. So this should make you feel pretty good that even if you're not doing testing, you don't have to worry so much about having a child with a chromosomal problem. Yes, by testing them you do reduce that risk. But the point is even when they are abnormal, they usually will not make it to a live birth. So let's talk about that a little bit more. There are several reasons why anemlanted embryos do not lead to a live birth. There are basically biological barriers that prevent them from developing successfully. One of the first ones is can be failure to implant due to the genetic imbalances that disrupt the normal cell division in early embry development. And thelated embryos have a much lower chance of implanting. Many of them will not progress past the point ofB Blastocys stage and will not keep growing. So for many patients they won't even get a positive pregnancy test. Now clearly, having abnormal chromosomes doesn't make the embrya just stop growing all the time, because if they made it a blastocyst, clearly they can be abnormal and still keep going a little bit of a distance. And that depends where the chromosomal problem is. If the chromosomal problem, let's say, is in the beginning of the DNA, when a lot of the cells are dividing, then it's going to stall early and it's not going to implant. But what if the DNA was abnormal later in the DNA, maybe past the point of this division, when you start getting into things like developing organs? Well, then in that situation, it may implant, but it may lead to an early pregnancy loss, such as a miscarriage, because the body is going to recognize that the chromosomal abnormalies are going to lead to defects in the embryo. And those defects are either going to cause the embryo to succumb to that, or the body will, at that point, stop the pregnancy. So in the situation where, let's say there are minor problems in the chromosomes and the embryo implts but it then stalls, the body will realize that the embryo is not growing anymore and will then pass the embryo through a miscarriage. Now, even further along, there could be some type of developmental arrest. For example, let's say when the heart is being developed and maybe the chromosomal abnormalies are causing the heart to develop abnormal, that can then lead the baby to pass, because the heart cannot support the embryo at that point, you can get a later miscarriage. Some of these chromosomal abnormalies can disrupt the formation of things like the placenta, not just the heart. And that can then lead to problems that affect the developing embryo. And then the last thing is going to be things like lethal genetic disorders. So these are going to be things that prevent a pregnancy from being viable. These are the things like any chromosome disorder, other than like 13, 18, 21 and Turner's syndrome. And that's because most of these chromosomal disorders are not compatible with life. And so again, they won't make it to a live birth. Now, what's interesting is some types of chromosomal disorders have a better chance at a live birth than others. For example, Klinefelter syndrome, most of the embryos will end in the miscarriage, but it will have the highest chances of a live birth if you put back embryos, just like down syndrome has a very high liveirth rate compared to other chromosome disorders. So, for example, if you put back a hundred embryos with klelinefters, unlike down syndrome, which would have two live BIR per 100 embryos, you would actually get closer to six. And thats because it has a higher chance of resulting in a live birth. But other chromosomal disorders, such as Turner syndrome, you would not even expect one live birth per 100 embryos. It would take about 500 embryos with Turner syndrome to get one live birth. If you put back embryos with trisomy 13, you would take 400 embryos to get one live birth. And if you put back trisomy 13, it would take about three to 400 embryos to get one live birth. The point is, even when the chromosomes are abnormal, the likelihood of ling to a live birth is very low. So when people say things like, well, I would be okay with having a child with downstrome, why can't I put that embryo back? The reason is because the chances of actually coming away with the light birth is still very, very low. Same thing when it comes to things like Turner'syndrome Overall, the point of this podcast was to help those who are worried about the idea that they have a high risk of having a child with a chromosomal disorder, because their PGT results showed that they make lots of abnorl embryos. And so in their mind, if they're 45 and have a 95% chance of having anaplo the embryos, then it's not unreasonable to think that you also have a high risk getting pretnaturally of having a baby with a chromosomal problem. But clearly the chances are actually quite low. What most people don't realize is younger people end up having more babies with down syndrome than women who are more mature. Now, statistically it's lower, but because younger people have more kids, they actually have more babies with down syndrome. And the reason why we like to use down syndrome as an example of chromosomal abnormalies is because it's the highest one of having a child with that most people are concerned of. Although klelinefeltder has a higher chance of being born, the medical implications are much minor. The second goal I would want from this podcast is for people who are concerned about what if I get an embryo that has down syndrome and that I'm okay with that embryo being put back just like an embryo with Turner'syndrome and so, although most clinics and very few will allow you to put that embryo back, it's important to understand that statistically speaking, it probably would have never worked anyways. And that as we talked about, it would take at least 50 embryos to put back until one took. And that's even they have a live birth with a child with downstroam. that's not even talking about what the risk to the baby would be. I do think it's important for people to realize that although many patients are worried about having a child with a chromosome problem like downsttrom, many of us also wouldn't be the end of the world because it's still a baby that's going to love us. And I know many people feel that way. And so I don't want anyone to take from this that it's bad to have a child a chromosomal problem. It's just that some people, maybe they're later in life having kids may not have the stamina to be able to work with a child in that situation. And so for them, they want to help prevent it. But I do think it's important to know that there are many, many children born with chromosome abnormalities that bring a lot of happiness to everyone's life as well as their own. This podcast was just provided to give you an idea of the statistics and the chances and that for you to know that what comes out of the PGT testing is not what we see in reality. And that's because the point of chromosomes leading to a live birth is not directly correlated since most of the embryos will not make it to live birth. Well, hopefully someone found this podcast helpful. Maybe you didn't know the statistics for each one of these things, or maybe you didn't understand this. Maybe you're one of those people who got a lot of anaploid embryos in your PGT results and are thinking I'm afraid to have a kid naturally. And now you can feel comfortable that the chances still are quite safe and you don't have to worry about that. If you are someone who does have anaploed embryos and you do want to transfer them, there are some clinics out there that will transfer abnormal embryos even once it down synd them, but they are far and few. What I would tell someone is if that's something that's going to bother you and you don't feel comfortable not using those embryos, you probably shouldn't do PGT testing and just leave things to natural chances as I always mentioned. I appreciate everyone who supports this podcast. Please tell people about it so we can make this one of the top podcasts around and educate our fertility family so they can become strong advocates for themselves. If you love us, tell your friends about us. Give us a five star review on your favorite medium. But as I keep saying, the most important thing is to keep coming back. I look forward to talking again next week on Talk about Fertility Tuesday.