Double the Joy, Double the Risks: Understanding Twins in the World of Fertility

In this episode of "Taco Bout Fertility Tuesday," Dr. Mark Amols dives into the fascinating and complex world of twins. Whether you've dreamed of having twins or are curious about what causes them, this episode covers it all—from the science behind fraternal and identical twins to the cultural perceptions that make them so special. Dr. Amols also discusses the increased risks associated with twin pregnancies, why the medical community is cautious about multiple births, and the evolving practices in fertility treatments aimed at reducing these risks. Join us as we explore the joys, challenges, and everything in between when it comes to bringing two into the world. Don't miss this insightful and educational episode!

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Transcript

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Today we talk about the fascinating world of twins. I'm Doctor Mark Amos, and this is taco. About fertility Tuesday, twins. I remember when I first found out I had twins, I thought, this is amazing. And, to be honest, when I was younger, I used to think I would have twins. And it's funny because I hear that a lot. A lot of people think, yeah, I think I'm supposed to have twins. And they kind of dreamed of it. And I don't know if that's because for those of us who have infertility, we start thinking about twins. Because for a. A patient who has infertility, twins is not something you're scared about. It's actually a blessing in some ways. You've worked so hard to get pregnant that if you get twins, you think, hey, two for one, financially. But also, you know, your kid always has a friend because now they have a sibling. And so today I wanted to talk about twins from a different standpoint. I want to talk about twins from the standpoint of how common are they, what causes them, the science behind them, and why the medical community is so against them. The first part we should start with is, what does it mean to be a twin? Because we know there's these twins that are fraternal, and then there are twins that are identical. And the world's fascinated by twins. I mean, they have movies about twins. You got Arles Schwarzenegger and Danny DeVito doing a movie about twins. I think one of the first places to start is understanding the difference between fraternal twins and identical twins. Fraternal twins is what we call dizygotic twins, meaning from two different zygotes, whereas identical twins come from one zygote, which we call monozygotic twins. Now, this seems like it's pretty self explanatory. Most people should know the difference. But I actually have a very funny story. So years ago, when we had my daughters, everywhere we would go, everyone wanted to see them. And we were in the mall of America in Minnesota, and this lady came up to us and said, oh, identical or fraternal? I immediately said to her, oh, they're identical. And then she said, same sex or girl? Boy. It was at this moment that I realized not everyone understands the difference between dizygotic and monozygotic twins, because if they were truly identical monozygotic, there's really no way they could be two different sexes. And that's because they come from the same egg and same sperm. So they'll be the same sex now. Yes. There can be developmental things that can happen, but in general, I realize that it's not as common of a thing people understand. So why did she ask it? Well, it's kind of like one of those things we just ask. When, people are, twins, you just so identical or fraternal, just like when someone has a baby, you say, well, what was the weight? Why do you care about the weight? You don't really care about the weight, but it's just one of those things. You ask how big they were and stuff like that. Now, throughout the world, there has been an increase in twins. Now, the most common type of twinning is going to be fraternal twinning. This is a situation where a woman releases two eggs and then you can get two pregnancies from it. Now, the more common cause of fraternal twinning in the world is because of two reasons. One is going to be infertility, having fertility treatments and putting back two embryos, or making multiple eggs with an iui treatment. The other reason is that as women get older, their body starts to release more FSH and can sometimes cause an ovulation of two eggs, and that can lead to a higher chance of twins. Matter of fact, in Nigeria, there is a higher risk of fraternal twinning, where one of every 22 pregnancies ends up being twins. Now, what's interesting to understand about twins is that when you see fraternal twins, this runs on the female side. So a lot of times I'll hear people come to me and say, oh, well, my husband has twins in his family, so we have a higher risk of twins. That's not true. It doesn't run on the male side, it runs on the female side. So if your mother had twinsd, if sisters have twins, then their babies will have a higher risk of having twins, and that is because they release more than one egg when they ovulate. Now, identical twinning is a little bit different. That really doesn't change between different cultures or different people. It's generally about the same, which is about three to four for every thousand pregnancies. But what's interesting is, over time, as twins have increased, the increase is mostly from the fraternal twins, and identical twins have pretty much stayed about the same. Now, we have seen increase in identical twins in IVF treatments, and we believe that there might be some things with assisted hatching and ICSI that may cause a slightly higher risk of twinning. But in general, you are not wrong. You are seeing more twins, and that is because it has been increasing over the years. To give you an idea of the differences, back in 1970, there was approximately 18.9 twins per thousand births. Now, in 2020s, there's 32.1 twin pregnancies per thousand births. Now, when it comes to fraternal twins, it's pretty obvious. There are two eggs, two sperm. These are two completely different humans. But when it comes to identical twins, monozygotic twinning, they are technically from the exact same DNA. But as you know, there's different types of twins. For example, you'll see twins that are in the same sac, sometimes, sometimes even conjoined. And so let's take a minute talking about how twins occur. So for fraternal, again, it's releasing two eggs, whether that is with medications such as clomid or femara, or whether it's just naturally. When it comes to monozygotic twinning, there are basically four different types of what we call placentation, or presentations, which would be one is called monochorionic diamnionic twins. There's another called dichorionic diamnic twins, and then the last one's called monochorionic M. Monoamnionic twins. So let's talk about each one of those. The first word is talking about how many placentas there are. So if it says dichorionic, it means there's two placentas, and the next part is talking about how many amniotic saxers are. So if it's dichorionic diamnionic, it means they have their own placenta, and they have their own amniotic sac. Essentially all fraternal twins are going to have dichorionic, diamniotic placentation. For identical twins, this is approximately 20% to 30% of the pregnancies. This is going to be one of the more safer pregnancies for identical twins and will have the same risk of basically fraternal twins because of the placentation. Now, the next category is going to be monochorionic diamniotic twins. So monochorneotic meaning one placenta, diamnioc meaning different amniotic sacs. This makes up about 60% to 70% of the other type of identical twins. And this one does have more risk because they share the same placenta. And that puts some risk for twin twin transfusion, which occurs in approximately 15% to 20% of the pregnancies. The last type of placentation is going to be monochorionic monoamniotic twins. And this is exactly what it sounds like. One placenta and one amniotic sac. This is one of the rarest forms of identical twinning, which occurs in about one to 2% of identical twins. And because they share the same amnioc sac, there is extremely high risk to these pregnancies, where approximately 50% of the pregnancies may end in mortality of the twins because their chords can twist between each other. But I said there was four. Well, there is a fourth type, and that is going to be conjoined twins. Conjoined twins are always going to be monochorionic, monoamniotic, because to be conjoined, you have to be in both the same amniotic sac and the same chorion. When it comes to conjoined twins, it occurs only about one in 200,000 live birds. So it's very rare occurrence. There are risks, just like the monochorionic, monoamniotic twins. But the cord getting twisted doesn't happen as much because they can't both move independently. But there are very complex medical cares and significant health challenges that they have. And so it also has a high morbidity mortality rate. So what makes one over the other? Is there something that happens? Well, there is. It has to do when the embryo splits. If the embryo splits in the first three days, it will be dichorionic, diamniotic, meaning the embryos splits so early that the placentas and the baby amniotic sac are going to be completely independent of each other. And again, that occurs in about 20% to 30% of types of identical twinning. Now, if the embryo divides between the fourth and 8th day after fertilization, then this is where you get the monochorionic, diamniotic twin. So the babies are in their own sac, but the chorion wasn't able to split because it developed a little bit later, and so now they share the same placenta. This is the situation where it's about 60% to 70% of identical twins and has the risk of twin twin transfusion, a higher risk pregnancy, compared to, like, fraternal twins or diamnionic twins. Now, if it splits between eight days and twelve days, then there's a good chance they're going to share both placenta, amniotic sac. And this is the one I was telling you called monochorionic, monoamniotic twins, which is rare, about one to 2% of identical twins, but carries significant risk due to the possibility of the twins umbilical cords becoming entangled, and again with a 50% risk of mortality. So it's very scary when we see this. Luckily, we don't see it that often. Now, if the split occurs after day twelve, such as at 13 past, then there is a risk of having conjoined twins. So, as you can see, the splitting and the timing of the splitting is really what determines what type of placental, amniotic division that will occur and whether you're going to have dichoric, diamniotic, monocoric, diamniotic, monocoric, monoamniotic, or conjoined twin. Some of these are just referred to as di di mono di monomano, or conjoined, to make it simpler. So one thing that's really interesting about twins is the cultural perception of twinsd. Throughout the world, different cultures have different thoughts about twins. For example, in the Navajo culture, it is often regarded as a sign of great fortune. Some of the Navajo myths describe twins as children of the sun God, indicating their special status in divine origin. The Hopi people also hold twins in high regard, believing that the twins have a special bond with nature and the spiritual world. In Asia, Japan used to see twins as a bad omen due to the belief that they defied the natural order. However, over time, today, twins are generally celebrated in that culture. But in China, twins are seen as a double blessing, particularly if they are a boy and a girl. The belief is that such twins, such as boys and girls, bring balance to the family. In South America, the inca civilization believed that twins were sacred, and it had a special role in their society. In Europe, they were seen as possible connection with gods. And in other countries, theyre believed to possess special spiritual powers. The point is, it doesnt matter where you are in the world. We all realize that twins are special, but unfortunately, sometimes double the joy also brings double the risk. Whenever I get asked, what are the risk of having twins, I tell everyone, it's easier for me to tell you what won't happen than to tell you what will happen. And that is when you have twins, rarely do you get big babies because they're delivered early, and rarely do you get late babies because, again, they deliver early. But everything after that does occur at higher risk, meaning things from gestational diabetes, preeclampsia, birth defects, and almost anything you can think of increases with twins. Now, it's important to understand these are increases. They're still absolute small increases, but that changes the difference between the type of twins you have. If you have fraternal twins, the biggest risks are going to be preterm labor, and then the other risk is going to be an increase in all the general risks that come with pregnancy, such as gestational diabetes and preeclampsia and so forth. But identical twins have another risk that fraternal twins do not have, and that is twin twin transfusion. We talked earlier about the placentas and how they can be di di mono di, or mono mono now. Didi, amniotic twins, which are the less common ones, those are the ones that split within the first three days, are not going to have the risk of twin twin transfusion, because both of the embryos have their own placenta and own amnion. The risk of the cords get entangled are very low because again, they're in different amniotic sacs. So their risk can be very similar to fraternal twinning. But monochorionic diagnostic twins do have a higher risk of having twin twin transfusion. As I mentioned, at least 15% chance of having twin transfusion. This is the situation where the embryo splits between days four and eight. Now you have all the risks that come with twins, and you have an additional 15% risk of having twin twin transfusion. And there are ways to treat that which is beyond this podcast, but they're very difficult to treat. And basically, if it happens before 28 weeks, it can be very concerning. If it happens after 28 weeks, at least the baby can be delivered early. And so you can help. But some of the treatments they have out there dont always work and can even sometimes lead to mortality. Monochorionic monoaminiac twins are the ones I always hate seeing because I know theres a 50% mortality rate. So now, again, you have all the risk of having twins. You also have the risk of twin twin transfusion, and now you have this high risk of the babies entangling the placentas, which again leads to at least a 50% mortality rate. As you can imagine, conjoined twins even have all these things and then added on to all the complexities of the medical complications that occur with it, depending on how theyre connected. The good news is, most twins do fine. And I dont want you to feel ominous, just because you have twinsd. But there is this push in the society to reduce the risk of twins because with them comes complications. Twins need more prenatal care. They need a specialist, usually involved when it comes to delivery costs. It's much more expensive to have twins. Even the hospital stands at being longer because a lot of times these babies are born early and so they have to stay in the NICU or level two nursery that cost more money, even the type of delivery changes a lot of time. Twin pregnancies end up in, in a c section because of potential risk or if one baby is coming out breech. And so the reason why there is this community trying to reduce the risk of twins is because there is a risk whenever you have a twin pregnancy, both during the pregnancy and even at ah, delivery. So there is this push to have single pregnancies, but there is also a push financially by a lot of insurances because they know there's a higher cost with twins. And so it's coming from multiple angles. In the end, we have got such high pregnancy rates now that I do believe it's always best to put back one embryo. Now, again, you can still get twins from splitting, and I still think there's a place to put back two embryos. But the biggest change I have had is that in the beginning I didn't care if people put back two embryos. But now I realize there is actually an advantage to putting back one embryo, especially when you have few embryos. And that takes us to one of the last parts of this talk tonight, which is now you have this decision, maybe your clinic does allow you put back two embryos. Should you? And what I would tell you is this, yes, putting back two embryos is going to give you a higher chance of coming away with one pregnancy. But if you only have two embryos and you put them both back and something happens, such as bleeding, some complication of pregnancy, and you lose both embryos, you have no more embryos. Versus if you put one back at a time, anything that happens to that embryo is not going to affect the other embryo. Which means the cumulative pregnancy rate of putting back one embryo at a time will actually give you a higher chance of a live birth than putting back two at the same time. I dont regret my twins. As a matter of fact, Im so happy to have them. The purpose of this podcast today was to help people understand twins a little bit better, understand how they occur, and understand that there are risks and why there are different risks for different types of twin pregnancies. One of the things you're going to notice is more and more clinics are going to start going to single transfers, not just because it's safe for the patient, but also because there is really a push, even from the insurances making all clinics go to that. And although I don't like the idea of government or insurances telling people what to do, because we're adults and should be able to make adult decisions, I do have to at least take a step back and say it is the safest thing to do for that reason. That is why I do tell all patients it's probably best to put back one embryo at a time. This doesn't mean there's not the times to put back two embryo. There are, and that's something you have to talk to your doctor about. And it's not wrong. If your doctor decides to put back two embryos, they're allowed to do that. The point is that if it's a great embryo, it's always best to put back one at a time. And if it's a situation that there should be more than one, then you're talking to your doctor and they're going over those risks or your situation of, why more than one is better at that moment. Hopefully this episode was educational for some of you. Maybe one of you were one of those women I met at the, Minnesota Mall of America. Either way, I hope you learned a lot from this, and maybe you have a friend who's interested in learning this topic. Tell them about it, too. Maybe you have a friend who has twins or has a friend who thinks they're going to have twins. Maybe just going for Tully as worried about twins. This podcast was specifically just to give some education. And if you do have twins, you're part of a special club. And as you know in the world, your kid may be looked at as a God. What I can tell you is that you have in common with every person who has twins is you probably didn't sleep a lot in the first few years. As always, if you like the podcast, please tell a friend about us. Give us a five star review on your favorite medium. But most of all, keep coming back, and I look forward to talking again next week on talk about fertility Tuesday.