Multiples

why is it my dr. doesn't know if they are ferternal or identical?

I've seen siggys that say FT or IT at like 10/12 weeks gestation. How can this be since you can't tell the sex. And even if they are the same sex, how would you know they were FT or IT?  I thought to see if they were identical, you had to have them tested when they get a couple months old. Am I missing something?

Re: why is it my dr. doesn't know if they are ferternal or identical?

  • Identical twins can have their own placentas/sacs so without knowing if they're the same sex or not, then you wouldn't really be able to tell.    

    If I remember correctly, at my NT scan they were looking at the membrane and how it was separated and from that, the Dr. had a good inkling that mine were fraternal before seeing the sex.  

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  • imagesara1014:

    Identical twins can have their own placentas/sacs so without knowing if they're the same sex or not, then you wouldn't really be able to tell.     

    So people that put they are having FT or IT in  their siggy before they are born......actually don't REALLY know if they are FT or IT?

  • At my 6 wk. u/s they saw 2 follicles on my ovaries which shows I released 2 eggs=fraternal.  They have also had a fairly thick wall between them.  They won't tell me 100% but are making an educated, confident assumption that they're fraternal.

     

    If I'm not mistaken, there are some identicals that wind up in the same sac and so those ones are obviously identical.

  • I could be wrong here, but the way I understand it is that my twins are identical because they share the same gestational sac.  At my u/s last week, we saw two heartbeats in the same gestational sac (meaning one split into two).  Fraternal twins are in different gestational sacs, meaning two different eggs fertilized.

    We are still waiting to see if my twins will share the same amniotic sac (mono/mono) or have different amniotic sacs (mono/di), and we hope to know this Monday at 8w1d. 


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  • I think there are ways to tell (that a doctor could explain since I heard him say it once, but then it became unnecessary knowledge for me after finding out mine were b/g).  Something about the membrane/division has something to do with it.  Someone who has heard directly from their doctor about their same sex twins would definitely be able to answer on that better!I would imagine if it's posted in their siggy then they have information that tells whether or not they're fraternal or identical.    
  • quite often, unless you are having b/g twins - it's impossible to 100% know until the babie are born and do DNA testing (or, in my case, if they have different blood types).  My boys also look nothing alike.

    US images are not fault proof - and even if it shows to look like they are fraternal, sometimes it just appears that way, vice versa.

    also, for me, we knew we had 2 eggs at IUI - so the chances were much higher that it was fraternal - since an egg splitting is a fluke.... doing IVF with 2 embies or IUI with 2 (or more) follies = most likely fraternal... though IVF with ICSI is thought to have a higher rate of ID's b/c the ICSI weakens the egg and it splits....

    ok - more than you needed to know.... just rambling :)

  • imagekimarino13:

    I could be wrong here, but the way I understand it is that my twins are identical because they share the same gestational sac.  At my u/s last week, we saw two heartbeats in the same gestational sac (meaning one split into two).  Fraternal twins are in different gestational sacs, meaning two different eggs fertilized.

    We are still waiting to see if my twins will share the same amniotic sac (mono/mono) or have different amniotic sacs (mono/di), and we hope to know this Monday at 8w1d. 

    from whAt I understand this is wrong

  • Interesting.  Then I am totally confused, since that is how my RE explained it to me.  Guess I will find out more next week.  :)

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  • At my 18 wk ultrasound (which seems like forever ago.....) the doctor in there was talking to the med students (I go to a "teaching hospital") and he explained that even though I've got 2 seperate sacs and placentas, there's a SMALL chance that they could be identical, but won't know for sure until the placentas are tested after birth. From what he said, it depends on how early the egg split that I could possibly have identicals instead of fraternal boys. I never knew that.
  • At my NT scan my Peri saw and explained to us that our twins are in seperate sacs but share a placenta which makes them identical and means that it was one egg that split.  Our egg split within the first 3 days which is why each baby has their own sac.  You can research all of this on the internet and also some twin books explain this to you.  In cases like mine and where the babies are clearly in the same sac the Dr can tell they are identical.  It's my understanding that where it gets confusing is when each baby has it's own sac and own placenta and it can go either way (Identical or not) and this is where many don't know until finding out the sex or even after birth through testing.  It is also my understanding that some people never know and choose to not have their children tested for whatever reason.  I don't think that anyone would put it in their siggy unless they knew somehow, like their doc telling them.
  • imageGoldie_Locks_5:

    quite often, unless you are having b/g twins - it's impossible to 100% know until the babie are born and do DNA testing (or, in my case, if they have different blood types).  My boys also look nothing alike.

    this is what i thought

  • There are lots of things that can give you indications early, so some people know when others don't.

    Some of the things that can tell you early if they are identical or fraternal

    Same gestational sac: definetly identical

    Different gestation sac: could be either identical or fraternal, but more likely fraternal

    Early ultrasound showing that you only ovulated one egg: definetly identical

    Early ultrasound showing that you ovulated more than one egg: most likely fraternal, but small chance identical

    IVF where you put in than one: most likely fraternal, but small chance identical

    Using clomid or other drug that can increase ovulation: most likely fraternal, but small chance identical

    boy-girl twins: definetly fraternal

    Once they are born, there are lots of things that can tell you for sure that they are fraternal such as different blood types or different eye colors.  

    Also, some people have several of the factors that make it most likely that their twins are fraternal, so they just start saying they are fraternal (that's what I did, but I wasn't 100% sure until they developed different eye colors).  

  • imagecands:

    There are lots of things that can give you indications early, so some people know when others don't.

    Some of the things that can tell you early if they are identical or fraternal

    Same gestational sac: definetly identical

    Different gestation sac: could be either identical or fraternal, but more likely fraternal

    Early ultrasound showing that you only ovulated one egg: definetly identical

    Early ultrasound showing that you ovulated more than one egg: most likely fraternal, but small chance identical

    IVF where you put in than one: most likely fraternal, but small chance identical

    Using clomid or other drug that can increase ovulation: most likely fraternal, but small chance identical

    boy-girl twins: definetly fraternal

    Once they are born, there are lots of things that can tell you for sure that they are fraternal such as different blood types or different eye colors.  

    Also, some people have several of the factors that make it most likely that their twins are fraternal, so they just start saying they are fraternal (that's what I did, but I wasn't 100% sure until they developed different eye colors).  

    you might have only ovulated one egg but couldn't it split afterwards? Thats how you get identicals anyway right?

  • Here is why I feel certain that ours are fraternal. They are di/di. We did a 5 day IVF transfer of two embryos. My understanding is that in order for identicals to be di/di the embryo would have needed to have split very early, like by day 2 or 3 after fertilization. Ours were still in the petri dish being watched by the embryologists until day 5, so we know they didn't split that early. So I feel pretty confident that both implanted and they are fraternal rather than identical. I'm definitely no expert, though. That's just what I've gathered from info I've read online!
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  • my doctor would never say for sure that mine were identical, even though it was very obvious from the first u/s that they shared a gestational sac. that's a very very very good indication that they're identical. it's pretty darn obvious on early u/s if your babies share a gestational sac.

    however, he still wouldn't give me a 100% answer. then again, the doctor i'm referring to is my MFM who didn't see me until 23 weeks, so he didn't even see my first 7w u/s firsthand. but i'll bet if he'd seen it, he would have told me mine were ID.

    in the end, we did DNA testing to be 100% sure.

    it's far easier to confirm IDs before birth than fraternals, since only IDs can share a gestational sac. 

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  • imagefrustrated and ttc:
    imagecands:

    There are lots of things that can give you indications early, so some people know when others don't.

    Some of the things that can tell you early if they are identical or fraternal

    Same gestational sac: definetly identical

    Different gestation sac: could be either identical or fraternal, but more likely fraternal

    Early ultrasound showing that you only ovulated one egg: definetly identical

    Early ultrasound showing that you ovulated more than one egg: most likely fraternal, but small chance identical

    IVF where you put in than one: most likely fraternal, but small chance identical

    Using clomid or other drug that can increase ovulation: most likely fraternal, but small chance identical

    boy-girl twins: definetly fraternal

    Once they are born, there are lots of things that can tell you for sure that they are fraternal such as different blood types or different eye colors.  

    Also, some people have several of the factors that make it most likely that their twins are fraternal, so they just start saying they are fraternal (that's what I did, but I wasn't 100% sure until they developed different eye colors).  

    you might have only ovulated one egg but couldn't it split afterwards? Thats how you get identicals anyway right?

     

    Uh, yes, and that is what she is saying.  Ovulating one egg but getting two babies means that egg split.  Unless you are Sammysangel and another egg snuck out of the batcave.

  • imageangelnscrubs7:
    At my 18 wk ultrasound (which seems like forever ago.....) the doctor in there was talking to the med students (I go to a "teaching hospital") and he explained that even though I've got 2 seperate sacs and placentas, there's a SMALL chance that they could be identical, but won't know for sure until the placentas are tested after birth. From what he said, it depends on how early the egg split that I could possibly have identicals instead of fraternal boys. I never knew that.

     

    This is my situation. They didn't test the placentas so I won't know for sure unless they look different or we do a DNA test. We go back and forth based on how they look right now.

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  • From our first u/s at 8 weeks right up until our appt. with the perinatologist last week, everyone has already told us that our twins are identical.  They are in the same chorion (share one placenta), but have a very thin membrane between them, which means they have separate amnions.

    If someone has twins in separate chorions and separate placentas (or even fused placentas), I don't think they could know for sure, since it is possible for identicals to have separate chorions. 

    Although, if someone has had amnio testing done, couldn't they already know for sure?

  • Since we found out about our twins at 19 weeks, we dont have an earlier u/s which might make it easy to determine ID or Frat.  My MFM and OB coukd not tell me if they are frat/ID and so we have to have a DNA test. 
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  • imagefrustrated and ttc:
    imagekimarino13:

    I could be wrong here, but the way I understand it is that my twins are identical because they share the same gestational sac.  At my u/s last week, we saw two heartbeats in the same gestational sac (meaning one split into two).  Fraternal twins are in different gestational sacs, meaning two different eggs fertilized.

    We are still waiting to see if my twins will share the same amniotic sac (mono/mono) or have different amniotic sacs (mono/di), and we hope to know this Monday at 8w1d. 

    from whAt I understand this is wrong

     

    She is actually very correct.

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  • CandS explained it very well.

    Also, in terms of the odds: 1 in 3 sets of twins is identical, and 1 in 3 sets of identical twins is diamniotic-dichorionic. So if you have di-di twins (like I do), there is a 1 in 9 chance they are ID. So when I was pg I told people mine were "probably fraternal, but we'll find out for sure after they're born; if they look like they might be ID, we'll do a DNA test to know for sure."

    As it turned out, they look quite different so we haven't needed a DNA test. 

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  • Just confirmed with my OB this week:

    There is no way to be sure until birth. Mine have their own sac and placenta and I had 2 mature follicles before IUI, so most likely they are fraternal. When people ask, I tell them fraternal.

  • Mono/Mono twins are the only case where it is 100% certain they are ID, right?
    Baby Birthday Ticker Ticker Mommy to twin girls, Ashlyn & Fiona, born at 34 weeks due to vasa previa.
  • Just throwing in my 2 cents.  I have identical triplets.  I was told that they were identical when they were discovered during an u/s at 17 weeks.  they shared 1 gestation sac but there were very thin membranes separating their amniotic fluid.  There was also one placenta.

    After they were born, the placenta was tested (standard procedure at that hospital) and I was told that it was just one placenta as they had always suspected.

    There is no doubt that my girls are identical and I don't need DNA testing to prove it.  1 placenta and 1 gestational sac. 

     

  • My peri told me they can't tell for sure because the various presentations of number of placentas and sacs.  Depending on when identical twins split they could share a sac and placenta or have two sacs with one placenta, one sac with two placentas or two sacs and two placentas.  So, although I'm having two girls, they tell me there is only a 30% chance that they're identical.  The only way to tell for sure is if they share a sac and placenta in utero or you do DNA after birth.
  • Sarah, I am so jealous that they tested your placenta.  My placenta was taken away for research since I had the stupid vasa previa. oh where oh where has my placenta gone...
    Baby Birthday Ticker Ticker Mommy to twin girls, Ashlyn & Fiona, born at 34 weeks due to vasa previa.
  • Since our ultrasound at 7 weeks our RE and our MFM Dr has told us that we have a set of identical and one fraternal since we put back two embryos when we did IVF.
  • I had a c/s early on (6w) and Dr. said based on how far apart the sacs were she thought they were fraternal.  Then one u/s tech showed me early on (8w) where it looked like I had ovulated twice.  I also had two cysts.  So they said they felt pretty sure that my girls are frat.  but of course they can't be positive.
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  • Yes.  Id's can split early enough that they can be di/di.  I think more frequently though di/di means frat.  but again really no way to tell w/o blood test or dna
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