So confused... ID or Frat?

atlb · November 2010

So, from the get-go, I have been told that I am most likely having fraternal twins. I don't know if the doc just assumed this because I took Clomid and Oed from both ovaries or what. But today I went in for a cervical length check, and the sonographer said "So they are identical, huh?" And I told her that I was under the impression that they were fraternal. She said it looked like they were sharing a placenta.

I fully admit that I am ignorant in all things multiple, but I guess I didn't realize it would be so hard for them to tell whether they are frat or ID! What was your experience? Is there a point in which you "know", or do you just have to wait until they come out?

BelleBaby · November 2010

We got pregnant from IVF and transferred 2 embies. Our first u/s showed 2 very separate sacks. Each u/s clearly showed the division between the 2 placentas. All of that made us 99% certain they were fraternal boys. We tested them at their 1st birthday and it was confirmed then.

If you find out at your 20w u/s that you're having b/g twins, then it's obvious. Same sex might make it more difficult. Even separate placentas can look like one if they're close enough.

Or you can wait until they're born and ask Pea-Kay. She's our resident ID/Frat expert here.

But unless you find out they're b/g, it's hard to be 100% certain just based on u/s. You'd likely need to test them after birth. Looks can be deceiving too!

macchiatto · November 2010

The wikipedia article on twin types is pretty helpful in explaining this. You should ask if your twins are di-di or not (e.g. if your first u/s showed that or not; you could have two placentas that have fused. I'm not sure how early that happens, but I know I was told at 11w5d--my first u/s--that they were di/di, so when I was told at birth that I had one placenta, I knew they must have fused). If they are di-di, the only way to know for sure before birth if they are fraternal is if they're different sexes.

PianoPlayingSarah · November 2010

From my first u/s at 17 weeks, we were always told that the girls were identical. There was one placenta and they shared one sac but had very thin membranes separating them. The placenta was tested after birth and confirmed to be one placenta.

It is possible for 2 placentas (frat) to fuse together and appear to be one. You wouldn't know that until after the babies are born. You can also have identicals with 2 placentas. Unless you find out you are having b/g, you may have to wait until they are born.

seattlestef · November 2010

At my first u/s the girls had 2 distinct sacs and placentas, but by 12w the placentas had fused so we wouldn't have known they were originally seperate until after they were born. We thought they were probably fraternal because of that first u/s and a big size difference, but at 18 months they are looking almost identical and I'm still not sure.

macchiatto · November 2010

seattlestef:
At my first u/s the girls had 2 distinct sacs and placentas, but by 12w the placentas had fused so we wouldn't have known they were originally seperate until after they were born. We thought they were probably fraternal because of that first u/s and a big size difference, but at 18 months they are looking almost identical and I'm still not sure.

They are SO identical.

That's interesting to know placentas can fuse that early. I had wondered but wasn't sure about that.

atlb · November 2010

Thanks ladies! I am reading through the wikipedia article now. This is all so confusing... I had an u/s at 4 weeks 1 day that showed 2 distinct sacs. The MFM that did my NT scan said he was "pretty sure" they were fraternal. The comment today just really threw me for a loop!

I'm going in tomorrow to find out the sex(es), so maybe that will answer my question.

pea-kay · November 2010

an early u/s is more accurate in determining how many placentas you have. i would say they are more than likely fraternal, since there was clomid involved. but you never know...