question on fraternal/identical

Okay, first let me introduce myself-I have been a lurker for a little while
I'm Tina, a work from home mom in Mass. I have a 2 year old daughter Amber and we're expecting twin boys late June.
My question is regarding fraternal and identical twins. everything I read says that identical twins can form their own placenta and amniotic sac if the egg splits early enough. My drs say that fraternal twins are always 2 sacs and identical are always 1. My twin boys are in 1 chorionic sac with separate placentas and amniotic sacs. I'm so confused-I would think they could be either fraternal or identical from what I've read. I don't think the hospital/insurance tests unless there is a medical reason for it but of course we'd want to know when they're born. If they look completely different we'd know but otherwise, how can we find out? I've heard of test kits you can send away for but they're very costly. Has anyone else been through this? I'd love to hear
Thanks

 

Okay, first let me introduce myself-I have been a lurker for a little while
I'm Tina, a work from home mom in Mass. I have a 2 year old daughter Amber and we're expecting twin boys late June.
My question is regarding fraternal and identical twins. everything I read says that identical twins can form their own placenta and amniotic sac if the egg splits early enough. My drs say that fraternal twins are always 2 sacs and identical are always 1. My twin boys are in 1 chorionic sac with separate placentas and amniotic sacs. I'm so confused-I would think they could be either fraternal or identical from what I've read. I don't think the hospital/insurance tests unless there is a medical reason for it but of course we'd want to know when they're born. If they look completely different we'd know but otherwise, how can we find out? I've heard of test kits you can send away for but they're very costly. Has anyone else been through this? I'd love to hear
Thanks

 

First of all...Welcome and congratulations on your twins!! I'm a little confused about this: quote:
My twin boys are in 1 chorionic sac with separate placentas and amniotic sacs.
I've understood that if there is one chorion then there is one placenta, so this doesn't seem quite right to me. You're right, though, about 20 to 30% of identical twins can have their own placenta. As far as the testing, I think that's a topic that has come up a lot (both here and on First Year or Parenting), so you could try to do a search.

 

quote:
Originally posted by sawyerkustomz:
If they look completely different we'd know but otherwise, how can we find out? Thanks


Their looks are going to change so much as they grow...you can't necessarily count on that as the determining factor. Sometimes weight can make a BIG difference in how they look. We don't know if ours are Id or frat, but when they were first born we immediately thought frats b/c they didn't favor much at all. At about 6 months to 8 or 9 months, we were starting to think they were ID, and now I would say frats again...we really need to test

 

You are correct and your doc is mistaken. Identical twins can be in their own sac and have their own placentas as well if they split early enough.

First clue about id or fraternal is one placenta or two- 1 always is id, two can be eihter

Same sex can be frat or id and different sex can only be fraternal (there are a few very rare cases of different sex id twins. Very very rare though)

Blood type after they are born-different types can only be frat, same can be either.

Testing is the last resort if there's still a question. Chorion is the medical term for placenta.

Becky
Id girls dd 6/2
monochorionic diamniotic

 

i would ask your doc to explain it again...my twins are in two amniotic sacs, but one chorionic sac (placenta) - so we think they're identical, although the MFM doctor said there could be two placentas that could have fused (meaning they'd be fraternal)

i've gotten three different explanations from three different docs!

 

wow, thanks for all the responses
I think I'm more confused now though, lol.
I thought the chorion referred to the lining of the uterus and the placenta was a separate thing. I see the dr tomorrow so I will ask again if they are id or fraternal. I had an u/s friday that the tech said they were in 1 chorionic sac but separate amniotic sacs and two placentas that were no where near eachother-1 on left, 1 on right. anyway, thanks again for all the responses, I'm sure we'll just have to have them tested when they are here although I'm dying to find out before

 

Mine were in two sacks and had their own placentas (which fused during my pregnancy) but we had them tested and they are identical Its amazing how little some doctors and nurses know about twins!!!

 

Congratulations on your twins and welcome to TS! There are still many doctors who are under the impression that 2 placentas automatically means fraternal twins. While it is more likely to be fraternal twins, they can still be identical as well. Becky covered a lot of ways that you can use to find out if they are fraternal or identical including blood type & sex. Many parents wait until the babies are over a year old before trying any genetic testing because you can often make a little better guess about whether they are identical or fraternal after they weigh more. My identical girls have a 3 lb weight difference but, as they have gained more weight overall, that difference has become a smaller percentage of their total weight so they look more and more alike.

 

As previous posters stated, one placenta (chorion)equals identical twins regardless if there are one or two amniotic sacs. Sometimes women may have two placentas that fused together to look like one on the ultrasound.

I have two amniotic sacs and one placenta. This is called Monochorionic twins.

 

I'm confused about identical and fraternal twins. Early on I was told that my twins (both girls according to early sonograms) are identical. Then recently, I'm 32 weeks, I was told they are fraternal. There is one placenta and two sacs. Can anyone enlighten me as to which they are? Identical or fraternal?

 

Okay, I've always read that one chorion equals one placenta equals identicals. Well, I just came across this and am now more confused.

http://money.howstuffworks.com/twin3.htm

It states that there can be one chorion and two placentas. However, as with anything on the internet, I'm not sure how accurate this is or where the information came from. I've never seen this on any other site. I think in the third picture where it says "fused placenta," it's more likely that it's a shared placenta.

Regardless, if there is one chorion, they are identical. The chorion is not the placenta itself but, rather, it forms the placenta.

BabiesMK3, if your babies do indeed share a placenta, they are identical. It sounds like they each have their own amniotic sac, which is the most common type of identical twinning (one placenta, 2 amniotic sacs). However, I suppose it's possible they they each have their own placentas that fused very early on. If the "diagnosis" of monochorionic/dichorionic is not made accurately early on, it could be hard to tell by 32 weeks.

 

Hi, I too am new posting here and recently was told I am having twins. I had so many questions, similar to yours, all of which were difficult for my regular midwife or OB to answer. I took it upon myself to make an appt with a high risk doctor, one who specializes in multiple births and I am ever so happy I did! She spent an hour and 20min with me and even drew diagrams! She explained to me that in the womb a sac filled with fluid develops from the edge of the placenta. The sac has two membranes, the outer membrane is called the Chorion and the inner one is called the Amnion. Mono means single, di means two. In my particular case, I have di/di twins..two chorions/two amnions. She still said I could have identical twins because there could have been either one egg that spit which would be identical or there could have been two eggs which would be fraternal. I am not much help on Monochorionic twins as I was asking about my own dichorionic but if I were you, I would double check with your ob for more clarity on this issue and if you are still confused I would definately go to see a doctor that specializes in maternal/fetal medicine or multiple births. I too live in MA and had no problem finding one here. Good luck!

 

Thanks so much duobambine I got really confused when people were saying the chorion was the placenta and from everything I'd read, the chorion was a sac outside of the amnion. Are you near Maynard at all? I ask because I'm wondering if the high risk dr you used might be close enough for me to go and see.
Again, thanks to everyone for responses. We'll see what the dr says today

 

My boys were as fas apart as they could be, they each had their own everything. I had two placentas, two sacs, etc.... All the Docs told me they were fraternal.

They are identical. Not only can NOBODY tell them apart, but we also had the test done. It came back identical.

Anyone that knows me on this board knows this in one of my biggest pet peeves!! Docs should not be telling women with same sex babies that they know they are fraternal. That is simply NOT TRUE!!!

I have a poll going on this on the Parents Forum. Currently it states that 70% of parents with same sex children were told theirs were fraternal, and out of those, 23% found out they were actually identical!

 

My DH and his family were so convinced that he and his brother were faternal even though they look so much alike, because they were not shaped the same. BIL's lungs collapsed at birth and he was a half pound smaller. So he is still shorter and he is hunched over because his sternum is sunk in. It wasn't until my DS saw his uncle for the first time and totally freaked out because there were two of his daddy that the family really started to doubt the whole fratneral thing.

 

Cristina- thanks for sharing. I don't get why the drs always say fraternal and can't just say they could be either and the only way to be sure is to test dna after they're born. Can you recommend a good place to do the DNA testing? Was it a kit you bought online?

 

My docs would not tell me if they are fraternal or identical. They said we would have to wait until after they are born and have them tested. I think that is fair of them to say. I am guessing they are identical girls since they have seen only one placenta from the very beginning which lessens the chances of two placentas fusing to look like one.

 

Looks like the questions are mostly answered but about testing...

I recently ordered from Affiliated Genetics -- the test was $150 + $10 S&H. They have been wonderful to deal with so far. There is also Proactive Genetics (which advertises on this website) and they are similarly priced. MANY other companies are charging much more for the same test.

The kit consists of a sponge on a stick for each person and you rub it in their cheeks to collect some cells and then press the wet sponge onto a piece of paper. Simple and painless. It takes just a couple of weeks from order to results.

 

I just wanted to "second" the whole 'chorion is not the placenta' thing, but is in fact the outer sac. Some people may not want to read these details, but when I had a miscarriage at 9.5 wks. everything came out whole. The little baby was floating in what I thought was the amniotic sac. Well, after it sat a while the sac broke but the baby was still in a smaller sac. So the outer sac was the chorion while the inner was the amnion. It was cool to actually see that for myself (although the loss was obviously very difficult). Just thought I'd share that.

 

Like the pp posted, we used proactive genetics. That was about 4 years ago, and it was $150. I do not know if they have raised the price. They were good, we had to have the test done twice, and so did some other Moms in the same "batch" as ours, because something happened to the storage.. Not sure. Anyway, we re-did it, free of charge, and it took a few weeks. It was a kit with medical swabs that we rubbed on their cheeks/gums. It was painless and easy...

I am so glad we did it!

 

quote:
Originally posted by Cristina:
My boys were as fas apart as they could be, they each had their own everything. I had two placentas, two sacs, etc.... All the Docs told me they were fraternal.

They are identical. Not only can NOBODY tell them apart, but we also had the test done. It came back identical.

Anyone that knows me on this board knows this in one of my biggest pet peeves!! Docs should not be telling women with same sex babies that they know they are fraternal. That is simply NOT TRUE!!!

I have a poll going on this on the Parents Forum. Currently it states that 70% of parents with same sex children were told theirs were fraternal, and out of those, 23% found out they were actually identical!


This is starting to become a peeve of mine too. I really think IDs must be more common than the drs think because 3 moms I know personally have ids that all had seperate placentas and were told they had frats. (you make at least 4 moms now) Mine we arent even sure are the same sex (keep your fingers crossed they will tell me today at my u/s!!) But we are pretty sure it is two girls, anyway I will probably have the test done just to know for myself after they are born... thanks for all the great insight all!!

 

Hey, just wanted to add that we just got our results and ours are ID. They had completely separate everything and implanted far, far apart so the placentas didn't even touch.

 

Drs should not say 100% either way id or frat until a genetics test has been done! My peri said most likely fraternal due to two placentas/inner and outer sacs etc. And they are definitely TWO very different looking kids!

BUT... my cousin's wife has frat boys (both very diff looking too). But their placenta fused so it appeared they were ID until they were born too.

So that's my 4 cents....

 

I had two sacs, two placentas and my girls are identical to our suprise. We had the test done after our doctor also told us they had to be fraternal. They had too many similarities and would get rashes in the same places at the same time. Birth marks in the same places. Hands and feet looked identical. Good luck to you know matter what they are, they are a miracle.

Dawn

 

Just one little sidenote on ways to tell:
I had an ultrasound early enough *5wks5days* to actually see the sac left on the ovary from which the eggs were released. They knew I was having fraternal girls because there were 2 sacs on my right ovary. Now granted many people would not be able to have this information, but it was very useful in knowing early on exactly what we were dealing with...

 

I hate to be a poop but you never know if both eggs got fertilized or if one did and it split. Just that sometimes nature can fool you and not all eggs read the book. Still may want to do the genetic testing.

Anyone else have thoughts on this or am I over analyzing??

Mj

 

We have identical twin boys. What is quite interesting to me is that during most of my ultrasounds, the technicians told me that it was highly unlikely that the twins were identical, they were almost positive that they were fraternal. For the first detailed U/S appointment, my husband and I decided to go to California Pacific Medical Center instead of our local hospital, where not only the doctors are some of the best, but also the equipment is state of the art. The technician there also thought that they were fraternal. HOWEVER, the doctor that reviewed all the u/s photos, came into the room to personally check me, because despite what everyone else had stated (including his own technician), he was the one and only doctor to beleive that they were identical.

I don't remember the details, but it has to do with the membrane. If the membrane is in the shape of the greek letter Lamda (which looks like an upside-down V) then they are NOT identical. He could not find that Lamda shape. So then he looked for the T-shaped membrane (I beleive it is called a Twin Peak). The membrane was very thin and difficult to analyze. But he strongly felt that they were identical. And he was the only doctor to insist on this (I guess there is something to be said about going to the best hospital with the best doctors). The reason that this is really important is because if the twins share the same placenta AND the amnio, this is the riskiest type of twin pregnancy, and you have to be monitored very carefully. My twins shared the same placenta but they each had their own amniotioc sac.

How do I know? We did not have genetic testing done. They sent my placenta to be analyzed after birth. At this point, they confirmed that it was one placenta, not two fused into one, and that the boys shared the same amniotic sac. I beleive that they were monochorionic but diamniotic. And this test of the placenta, WAS covered by my insurance.

Just thought I'd bring that up as an alternative to an expensive genetic testing.

I guess if everyone continued to be as confident that they were in fact fraternal, I probably would not have asked to find out, and I would have continued beleiving that they are fraternal till today... Although they truly look so much alike.

 

When I was pregnant, my doctor, nurses, and the ultrasound tech all said only fraternal b/c we had separate sacs/placentas. During my pregnancy I read that there was a 25% chance they could be ID. I asked my doctor and he said that is wasnt the case with my girls. After they were born, they looked so much a like and had the same blood type. When they were 4 months old, I just couldnt take it anymore and I ordered a DNA test. Turns out they are ID. It irritates me how they tell patients this and it isnt true!

I met a lady the other day at BRU who was pregnant with twins. She said that she was having fraternals and I asked why she thought they were fraternal and she said b/c they had separate sacs/placentas and her doctor said it was impossible for them to be ID. I told her my story and let her know that they could be ID. Guess it helps to educate just one person!