MoMo Twins

Joe Rawlinson by Joe Rawlinson - April 25, 2017

Here is a question that comes to us from Anthony. He writes, “My twins are in the same sac. I’ve heard that’s bad, and it really scares me. How common is this, and should I be so scared?”

Twins in Hospital

Well, Anthony, having twins in the same amniotic sac in mom’s uterus is a pretty rare event. We’re talking one in several thousand twin pregnancies. Now, twins in this circumstance are called monoamniotic, monochorionic twins, or MoMo twins, for short.

There Will Likely Be Complications

Now, these types of twins are always going to be identical twins, and they do have a higher risk of complications due to this situation. Some of the risks include umbilical cord entanglement or twin to twin transfusion syndrome, known as TTTS.

Now, because of the higher risk of this pregnancy, it is scary. Fortunately, even though these twins have a higher risk of complications, they also have a very high successful birth rate. Due to the wonders of modern medicine, your wife and your babies can get some great prenatal care and help them come safely into the world.

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Take Special Care

Odds are, your wife is going be on bed rest and may even be in patient care in the hospital, so that the babies can be carefully monitored, particularly as the pregnancy progresses. And if there’s any situations that arise where the health of the babies or mom are at risk, then those babies are going to be delivered and they could be delivered very early.

And so, these twins are always going to arrive via Caesarian section.

MoMo Twins May Be Misdiagnosed

I have heard that oftentimes normal twins are misdiagnosed in the beginning, so make sure that your medical staff has indeed confirmed that this is the case for you.

Many parents who at first hear they have MoMo twins end up having normal twins later, and the diagnosis changed when further ultrasounds revealed the thin membrane between the twins. We had a very similar circumstance with our twin girls. We had a couple of ultrasounds with our twins before they could clearly see the membrane that divided the two amniotic sacs and made it very clear that our girls were not MoMo twins.

But it took us several ultrasounds and it was not clear in the beginning. Even to the trained eye of the medical staff, it was very hard to see that membrane.

So definitely confirm that this the situation with your twins, but then take heart and confidence in the fact that there’s great medical care available for Mom and for the twins to make it through this pregnancy.

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So Anthony, I wish you all the best with this journey with these twins. It will be challenging but with the marvels and the miracles of medicine today your babies have a great chance of being born healthy and joining your family.

This question was originally addressed on the Dad’s Guide to Twins Podcast episode 18: Twin Taxes, Car Seats in Small Cars, Mo/Mo Twins.

Picture by Jeremy Miles

Further Reading

Dad's Guide to Raising Twins book
Don't forget to pick up a copy of the definitive guide to raising twins. "Dad's Guide to Raising Twins" was written for fathers of twins to help guide you through the first several years with twins. Click here to learn more about the book and get your copy.

7 thoughts on “MoMo Twins”

  1. My two year old twin girls were mono mono twins. We were very nervous but survival rates are so much better now. I was impatient for 8 weeks for monitoring before they were born. It’s difficult but so worth it.

    • We’ve just had our 7.6day scan and found out we are having twins and they are MOMO twins. Obviously I’ve gone away and read about it and am not so petrified. It’s so hard to remain positive and so hope they do find a membrane separating them. We’ve been trying for a baby for 1.5yr, so it’s really taken the excitement away.

  2. The assumption is MoMo until a membrane is found and in the majority of cases, it is. Where it’s not found, your wife/partner will be monitored VERY closely (possibly rising to a couple of scans a week to ensure all is well) and early planning.

    Don’t worry needlessly – there’s plenty already going on for you to panic about without the added stresses MoMo’s bring. Let the medical staff do their job and you concentrate on yours – being an excellent partner and source of support.

    After all, post-natal, you’re not even going to think back to these worries – largely because you won’t have time…….

  3. Our girls started off as mono di but the membrane ruptured around the 12 week mark making them treat the pregnancy as momo. We delivered via c section 34 weeks there was 3 knots but my girls were thankfully healthy, no NICU and released with me 3 days later.

  4. Just found today (13 weeks 6 days) our twins are MOMO and we are understandably concerned, not only of the high risk of complications, but also the fact we were told they will want to do a C section at either 32 or 33 weeks. I’m curious about how often it is mis-diagnosed. Is the membrane often hard to detect?


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