Vanishing Twin Syndrome? Mono/Mono or Mono/Di (TW possible loss)

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brandi3167

New member
Hi all,

Figured this sub may be a good place to ask this question.

I had my 8 week dating ultrasound on Friday and to my surprise the technician found two babies. Fetus A measured exactly 8 weeks on the nose with a strong 155 heart rate. Fetus B however is already measuring significantly behind at 6 weeks 2 days with a low heart rate of 70. Techinically its still an embryo. If it matters, this was a natural pregnancy conceived after 5 months of trying. I’m 30F.

Based on the report my doctor said she thinks it’s a mono/mono pregnancy. She said the prognosis of Fetus B is not good and it likely it will be absorbed by my body/the twin.

I’d be OVER the moon with one healthy baby from this pregnancy but online research has me terrified of the possible outcomes of vanishing twin syndrome. Especially with mono/mono. I’d particularly like to know:

1) Have you/do you know anyone who’s had a mono/mono or mono/di vanishing twin pregnancy and the surviving twin went on to be healthy? I worry about the long term effects of Fetus A if Fetus B is absorbed in the womb.

2) Will I face issues with genetic testing for Fetus A in the second trimester?

3) Is 8 weeks too early to diagnose mono/mono?

Looking for the good, bad and ugly stories so I can make an informed decision about how to proceed with this pregnancy in the next couple weeks.

Thanks!
 
@brandi3167 So I have didi twins (aka they had their own placentas and sacs and were totally seperate), but to my understanding with improved imaging technology we are learning that vanishing twins are much more common than we thought; many women had it happen and never even knew.

I think fetal demise can be risky to the surviving fetus if it happens later in pregnancy, so early on I think it’s less risky. And as for the type of twin pregnancy - mono is incredibly rare, and yes, it’s hard to diagnosis.

Often twins are suspected of being mono only for the membrane to finally be visualized in the second trimester.

I’m sorry you’re going through this, I’m sure it’s scary and confusing, but I think your chances of bringing home one healthy baby are pretty good.

Oh - also on genetic testing - if your twins are mo-mon or modi that means they are identical, so I don’t think it should impact your genetic testing?
 
@johnvladimir Appreciate your perspective on this 🙏 I’m feeling optimistic that Fetus A is two weeks stronger and hopefully isn’t impacted if/when Fetus B is absorbed. And hopefully it will happen in the next two weeks instead of playing out later in pregnancy. The worst is waiting!
Re testing, my fear is when Fetus B is absorbed will it’s DNA still be present therefore effecting the results? Likely its delayed due to chromosomal issues.. so wondering if it’ll be flagged
 
@johnvladimir They are definitely not di/di as they appear to be in the same sac right now. High chance it’s identical if it’s mono/mono or mono/di. Do you think that if they are identical, even though Fetus A is developing wonderfully right now, Fetus A could also have a genetic issue/reason to stop growth like fetus B? I had assumed they’d be unrelated from eachother
 
@brandi3167 I am by no means an expert but to my understanding vanishing twins are very common even in identical twins (maybe even more common in identicals) - and many women that have that happen go on to have a healthy normal pregnancy.

So while I don’t know why, it would seem that vanishing twins in identicals are often caused by something other than a genetic issue, and furthermore, you should be able to expect to still be able to do an NIPT and it will not be impacted by the vanishing twin.

I think your chances of having one healthy baby are really good.
 
@brandi3167 Very anecdotal but a lifelong friend of mine was the surviving twin, the other vanished and she absorbed it. She had and has 0 health impacts, it’s just a fun fact she likes to share.

The knowledge of this phenomenon is increasing now that ultrasound technology is able to image so clearly, and so much is known about the pregnancy so much earlier in the process. It probably happened all the time before without people even knowing.
 
@brandi3167 Legit had to check the username because this is so close to our story and I’ve visited this sub a lot but didn’t remember posting! We found out we were pregnant with mono di twins at the 6w ultrasound but at the 8w scan baby B’s heart rate was 70 and they were measuring a week behind. My next appointment is in a few hours and I’m fairly confident they will only see one heart beat. Trying to just take comfort in the fact that it’s early so Baby A probably will be fine if we lose Baby B but it’s still a loss.
 
@losteve19 Oh wow!! Such a similar story to me. It’s such an emotional ride to be relieved for one healthy baby while also grieving the other twin. If you’re curious, I went back 1 week later at 9 weeks and they only saw 1 fetus, 1 yolk in 1 sac. There was zero evidence of a twin pregnancy.. it’s the strangest thing. I’m currently 11 weeks and now preparing for first trimester genetic screening. I’m crossing my fingers everything comes back normal/low risk. Do let me know how everything turns out with you. Stay strong mama ❤️
 
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