Identical or Fraternal?

Hi guys,

When we first had the 2nd heart beat detected, it looked like both embryos were in the same sac, does that mean they are identical?
Does anyone have ID twins, but one of each sex?

Thanks,
Mom2B

 

If they are in the same sac they are identical and will be the same sex. Only fraternal are b/g. You can also have fraternal same sex, but they wouldn't be in the same sac. Although you also can have identicals who are in separate sacs and have separate placentas!

 

QUOTE(HinSD @ Mar 6 2008, 11:59 AM) [snapback]655761[/snapback]
If they are in the same sac they are identical and will be the same sex. Only fraternal are b/g. You can also have fraternal same sex, but they wouldn't be in the same sac. Although you also can have identicals who are in separate sacs and have separate placentas!


Exactly.... we were lucky to know right away that we were having id's because they were very clearly in the same sac, with a separating membrane and shared the same placenta. My sister's twins each had their own sacs and placentas, but they had the same blood type (and were the same sex), so there was a 20-30% chance they were identical. She had their DNA tested and found out they were identical...

 

What are the dangers of having them in the same placenta and the same amniotic sac? I heard that this condition is considered high-risk. I'm still waiting for confirmation that we're having twins, but thousands of questions are coming up now... Thanks eveyone!!!

 

As others have said same sac means identical.

 

If they share a sac, they are def Identical - they are called Monoamniotic Monochronic Twins.

This is very high risk - my girls were Mono twins - The danger is because they share the same sac with no membrane separating them, the cords get tangled and knotted. I was on 24/7 monitoring from 26 weeks on and delivered via a scheduled c-section at 32 weeks. It is recommended that mono twins be delivered at 32 weeks.

Please let me know if you have any questions - it is a hard pregnancy but doable.

 

Thanks guys!!!

I'm going for an u/s on Monday to confirm and I'll ask the Dr.
What's interesting is that my dad and my sister have the same b-day and if my twins are born at 38wks, they can all have the same b-day. If they are born at 34 wks, there's a chance they could be born on my husband's b-day and at 35 wks on my b-day! But then, it's way too early to think about it. I'm only 10 wks.

 

QUOTE(Mom2B @ Mar 6 2008, 02:59 PM) [snapback]656166[/snapback]
What's interesting is that my dad and my sister have the same b-day and if my twins are born at 38wks, they can all have the same b-day. If they are born at 34 wks, there's a chance they could be born on my husband's b-day and at 35 wks on my b-day! But then, it's way too early to think about it. I'm only 10 wks.

Wow, that is interesting. Looks like they might share a b-day with someone else, besides their twin.

 

Im having 2 girls who are in different sacs, the docs said the only way to know at this point if they are identical is to get a DNA test, even if they look exactly alike they could still be fraternal.... because they couldve started as one and split off

 

My boys were in two sacs, two placentas and still have the possibility of being identical. Same sex, same blood type... I have not had them DNA tested to find out. As babies they were so identifical but now they look nothing alike!

 

I have 2 placentas and 2 sacs and I asked the doc if he thought they are id and he said no because the linings are to thick. Does that make sense to anyone?

 

QUOTE(Mom2B @ Mar 6 2008, 11:31 AM) [snapback]655701[/snapback]
Hi guys,

When we first had the 2nd heart beat detected, it looked like both embryos were in the same sac, does that mean they are identical?
Does anyone have ID twins, but one of each sex?

Thanks,
Mom2B


I am almost 29 weeks pregnant with identical girl twins. They are in the same sac, but have seperate sacs with in
that sac. They share the same placenta. I'm here in the hospital for cervix issues. I just asked the Dr. about
delevery. He said the 1st baby if head down is fine usally, it's the second baby that has stress with delivery.
So that's where a c-section comes in. If identical and in the same sac, they will be looking for a membrane.
That's important. If not, they are monoamniotic. And like the lady that said below , it is dangerous. You need
to be closly monitored. But look at me- I've been here on other issues! Aggghhhhh.....

I've asked the specialist before- it's very rare to have fraternal with identical twins. They are mostly same sex.
As you farther along, you should ask about the Twin to Twin Syndrome as well. Are you seeing a specialist?

 

my dr said that is doesn't matter if they are in the same or seperate sacks they can still be identical and you won't know til birth unless they are boy/girl then obviously they are not identical.....he said they used to think they had to be in the same sack to be identical but that's not the case they are finding more and more cases that aren't.....

 

Blood type, too - if they have different blood types they are fraternal. cvaughn - your doctor's comment does make sense - something about was it actually two sacs or was it one that split early (which would cause a thinner membrane). Someone with ID's can probably answer that.

 

yep they can look very much alike even more than identical but my Dr said that if this is the case the only way to know is if they do blood work (DNA) testing

 

Thanks everyone!!

Tina: I haven't been sent to a specialist yet, I'm going in for an u/s tomorrow to confirm that I'm having twins. So far, the u/s at 8wks showed 2hbts. Then I don't know what happens, but the nurse at my Dr.'s office did talk about them sending me to specialist!
I just want healthy babies!


Thanks for all the info everyone!!!

 

QUOTE(Mom2B @ Mar 7 2008, 05:14 PM) [snapback]658154[/snapback]
Thanks everyone!!

Tina: I haven't been sent to a specialist yet, I'm going in for an u/s tomorrow to confirm that I'm having twins. So far, the u/s at 8wks showed 2hbts. Then I don't know what happens, but the nurse at my Dr.'s office did talk about them sending me to specialist!
I just want healthy babies!
Thanks for all the info everyone!!!


I know honey- me too. All of this can stress you out a little. It's exciting but nerve racking at the same time with
the high risks involved. I saw a specialist at 8 weeks and they found the membrane that seperates the babies.
Seeing a specialist made me feel better because you get ultra sounds all the time. If I didn't see a specialist,
they wouldn't of probably caught my cervix issue with the OB. Good-luck! Keep us posted!!

Tina

 

I think it's important to know HOW twins can come about in the process to understand all the sac/placenta/identical/fraternal options. Here's a basic and easy run-down.

There are two common ways to have twins:

1. ONE EGG is fertilized by one sperm, then splits. - IDENTICAL
2. TWO EGGS are fertilized by two sperm, separately. - FRATERNAL

#2 is easy - there's a 25% chance of XX/XX (two girls), a 50% chance of XX/XY (girl/boy), and a 25% chance of XY/XY (two boys). (The 50% chance of XX/XY is actually 25% XX/XY (girl/boy)and 25% XY/XX(boy/girl), but the result is always one girl and one boy) This is why there are more boy/girl twin combos than girl/girl or boy/boy! This is also the only type of twins that run in families.

#1 is a little more complicated, but we'll get through it painlessly....
If the fertilized egg (called a zygote) splits very early (in the first two days after fertilization) they develop separate placentas and separate sacs.
If the fertilized egg splits after two days (this is the most common) they develop one shared placenta, but two separate sacs.
Very very rarely (1% of twins), the zygote will split so late that there is one shared placenta and one sac. This can be a risky gestation with a high chance of Twin-Twin Transfusion.
Extremely rare is the splitting of the zygote even later, which can result in conjoined twins.
Identical twins are always the same sex because they share the same genetics.

That is it, basically.

There is one other type of twinning I have recently read about that was recently discovered. It is rare. They are called semi-identical twins. It happens when the egg is fertilized by two sperm and then splits! You can read about it here: http://www.livescience.com/health/070326_semi_twins.html

Hope this helps to clarify the twin phenomenon! Please feel free to add details if you wish or correct me if I made any wrong statements, as it is late, afterall

 

Loved the explanations! Helped a lot!
I'll ask tomorrow at my u/s appt and we'll see what they say!
Thanks!!!!