Identical Or Fraternal Twins

29 Replies
Jennifer - April 8

It means that you are having identical twins which are enclosed in one sac. The most riskiest of all twin pregnancies.


ashley - April 8

It means your having identical twins. Both babies formed in same sac


tiaeesha - April 28

how big does ur ovaers get when pregant with twins


kate trefethen - May 10

it means that they are either fraternal twins, or identical twins with a more defined membrane surrounding each of them. that is MY theory, anyway. I just began studying this in cla__s today, so I am not so sure that my answer is correct enough to trust it. ^.^!!


jay19 - November 23

hi, iv got one sac but 2 heartbeats, iv been told im having twins, im just 19 years of age and its my first pregnancy, one sac usually means identical twins.. good luck with the babies, im 8 1/2 weeks, goodluck


*X* - November 23

I see that this thread is quite old, but I just want to add something to it for the sake of those who read it later. A lot of people have said that two sacs means fraternal twins. While this is most often the case, I just want to point out that it is not *necessarily* the case. The most identical type of twins you can have, which occur when the egg splits very early, normally each have their own sac. These are "mirror image" twins, and they are quite rare.


shawnee - December 20

the doctors say i have two sacs and im only 2-3 weeks pregnant do u know if i will have identical or fraternal twins?


Crystal - December 21

Monozygotic twins can form in the same sac, if the zygote splits more than a week after implantation. It is entirely possible to have monozygotic (ident) twins with 2 sacs and 2 placentas. Someone said twins in the same sac were more at risk for becoming conjoined. Once the embryo has split, it's split, they can't "become" conjoined. They are at risk for twin-to-twin transfusion, as well as umbilical entanglement when monoamniotic. The only in utero way to know if twins are mono or dizygotic is an amniocentisis. Different genders are also indicative of dizygotic (frats), but as many moms will tell you, they sonograms can be misread. I have fraternals, boy/girl twins. The only way to confirm biologically identical twins is a DNA test. Even twins like Mary Kate and Ashley Olsen, who look very much alike, can be fraternals. (The Olsen sisters are frats) To the last poster, you are quite early along, it's really early to tell. I didn't find out I was having twins until my second trimester, and even then the only confirmed information the doc could give me was they were in separate sacs, and therefore would not be conjoined and were not at risk for twin-to-twin transfusion.


Rachelle - December 22

Is 5 weeks 4 days too early to see twins? My OB checked to day for twins due to high and quickly doubling beta levels. She said that right now she can only see one sac and one yolk sac, but too early for even heartbeat, and too early to tell if there are two. She says it there are two they are identical. Anyone else think this is "too early" or could they still be really close together and not identifiable? Thanks!!


nobi - January 8

well, i am only 15 but i know as far as most women having two saca isnt true only identical twins have the same sac but can also have seperate sacs, also if you havent had a n ultrasound and seen two babies you could be hearing your heartbeat.also, I am 71/2 mths pregnant with twins they are in different sacs but have the same placenta i am also trying to figure out does this mean I am having identical or fraternal.


to nobi - January 10

if they share a placenta they ARE id, but your placenta may appear to be only one placenta but actually be two that have fused together. it is difficult to to see this via u/s.


Supporia - March 13

I am 9 weeks and I am having twins. I have 2 sacs. I am I having identical twins or fraternal twins.


Corona - March 13

2 completely separate sacs normally means fraternal. However sometimes even id twins have 2 sacs & you won't know if they are id or fraternal until an DNA test is done after birth. If you find out they are 1 boy, 1 girl, then they are for sure fraternal.


onetwothree - March 13

About 1/3 of identical twins don't share sacs or placentas. It all depends on when the egg splits. The sooner is splits, the less they share. The later they split, the more they share with conjoined twins being the severe end of that.



You must log in to reply.

Are you New to the forum? Sign Up Here! Already a member? Please login below.

Forgot your password?
Need Help?
New to the forum?

Sign Up Here!

Already a member?
Please login below.

Forgot your password?
Need Help?