We don’t talk enough about twins. Sure, we all know someone with twins; they’re adorable, cute, a mystery, and, as any twin parent will tell you, they’re an attraction on wheels.
What’s often not talked about, though, is the complications and the negative side of having these amazing and wonderful babies.
A twin pregnancy can be an isolating and lonely experience, with overwhelming information and, quite often, bad news. Especially in my world, the world of monochorionic twins – or twins who share a placenta.
Identical Twins
Identical twins happen in around 1 in 250 pregnancies. They’re not common, and the shared placenta can cause issues.
There’s a high risk of premature birth and problems related to the placenta, like TTTS, TAPS, and SFGR. (I’ll talk more about these below). Along with the stress of the complications, there are also financial, emotional, and psychological impacts on families expecting multiples.
There is so much that has to be considered when we’re talking about twins. The right screening must be done during pregnancy, discussing potential complications, treatment options, emotional and psychological support, and financial counseling. There’s also a need to discuss the long-term outcomes for these babies related to prematurity and specific diseases.
While websites exist and tell us that the research supports the different aspects of twin pregnancy, there’s a real need to talk about things in everyday language. I’m passionate about breaking down the barriers of medical terms and jargon and taking science to the streets. As parents, we need to know the details without a dictionary. It’s also important to know the details so that when you have to advocate for correct care or treatments, you can present the evidence in a way that you understand and put your case forward calmly and rationally. Having conversations about your care is a team scenario. You need to have the tools and resources to advocate for yourself and your babies and be able to use them effectively.
Twins And Rare Diseases
Rare diseases and twins? Am I joking? No. Twins who share a placenta are actually at risk of rare diseases. It’s a bit of a paradox. These diseases are considered rare, but you automatically move into a high-risk category once you fall pregnant with monochorionic twins. So, while on technical terms, for the general population, these are rare complications, for our community, they’re not. This is why close and careful screening is vital.
Statistically speaking, you have a 1 in 20 chance of developing TAPS, a 1 in 10 chance of developing TTTS, and a 1 in 4 chance of having some kind of growth discordance, including SFGR. But let’s have a chat about these diseases.
Twin Anemia Polycythemia Sequence
Twin Anemia Polycythemia Sequence, or TAPS, is a rare disease affecting monochorionic twins. It’s a disease of the placenta caused by tiny connections that pass only red blood cells from one baby to the other. It can happen spontaneously or after laser surgery for TTTS.
One twin is born with chronic anemia, with blood like rosé wine, and the other with blood that has too many red blood cells, making it thick like ketchup.
Screening for TAPS is controversial, with many guidelines worldwide still not supporting routine screening for various reasons. However, the evidence that exists after 16 years of research into this disease, TAPS is a serious complication. 1 in 4 donor twins in post-laser TAPS are at risk of dying just before or after birth, and in spontaneous TAPS, the donor twins are also at risk of deafness. With spontaneous TAPS, both babies are also at risk of developmental delays and impairments, with donors four times more likely to have these than recipients. Post-laser TAPS twins have similar outcomes to twins born after TTTS laser surgery. Followups are essential.
There’s a real need to talk about the realities of TAPS and update screening and educate the world about it.
Twin Twin Transfusion Syndrome
Twin Twin Transfusion Syndrome is the most well-known complication of monochorionic twins. It affects somewhere around 15% of these pregnancies. It used to be a blanket term for things like size discordances, color differences, as well as the fluid discordances, but as the research has evolved, we now know that TTTS is about fluid discordances. TTTS happens when one twin has too much blood (a high blood volume that causes them to create a lot of urine, which then causes an excess of amniotic fluid).
The other twin has a low blood volume, and so they produce less and less fluid. This causes them to become almost shrink-wrapped in their amniotic sac, and can cause death. The biggest difference here is that TAPS is about a difference in blood concentration – anemia and polycythemia – where TTTS is about blood volume – one baby is overloaded with blood, the other has very little. TAPS happens slowly, over time, TTTS happens rapidly, caused by a sudden shift in blood flow in the placenta.
The best treatment for TTTS is laser surgery, and you can find a great article about it here, as well as a video with a leading fetal surgeon about it.
Without treatment, TTTS is around 90% fatal. With treatment, survival rates for both twins jump to 60%, and survival for one twin is higher. It is vital that we do more research into treatments, and improvements are always being made in surgery techniques to improve survival.
Long-term outcomes for TTTS twins are around a 1 in 5 chance of mild to moderate neurodevelopmental impairment for donors and recipients, as well as any prematurity related risks. Once again, it is REALLY important to follow these twins up after birth.
Selective Fetal Growth Restriction
Selective Fetal Growth Restriction (SFGR, also known as Selective Intrauterine Growth Restriction sIUGR) is the final complication I talk about. Around 1 in 4 monochorionic twin pregnancies will be affected by size discordances, but when that discordance gets larger than 20%, and one twin falls below the 10th percentile in size, it’s classified as SFGR. Where TAPS is about blood thickness and small connections in the placenta, TTTS is about fluids and large connections in the placenta, and SFGR is about unequal placental shares.
One twin can have a larger share of the placenta, meaning things are not shared equally. It can also be caused by the umbilical cord not correctly attaching to the placenta. Treatment options for SFGR are controversial, but most research points towards close monitoring and a watch-and-wait approach.
The long-term outcomes for SFGR are a recent development, with a recent study finding that the smaller twin has a higher chance of mild neurodevelopmental impairment. As always, long term followups are essential!
Twin Risks, Complications, and How To Advocate
So now, while I’ve told you about these different complications, it’s also important to recognize them as different diseases. They all have different diagnostic criteria, disease progressions, risks, and long-term effects. We can’t label everything as just a form of TTTS anymore – because that’s inaccurate. They can also happen side by side, so ensure you get the right treatment options and long-term care. It’s important to have the correct diagnosis, so I want everyone to be talking twins.
Talking about twins is something I’m passionate about. I talk regularly on my social media about research, complications, and multiple births. To learn more, follow me or get in touch.