different types of twins

jls7284

is there any others besides identical and fraternal twins? someone asked me if i knew yet and if they are identical, what kind? are they refering to boy boy, girl girl or one of each? also how early can the OB determine what type of twins they are (if ever) thanks, and my apologies if these are silly questions!!!!!

jacobandcrystal

They may be referring to whether identicals share a sac or a placenta.  Our identicals are mono/di... meaning they share a placenta but have separate amniotic sacs. 

We knew at our 8 week u/s that they were identical and had separate amniotic sacs, and at our 10 week u/s they were just about sure that they are sharing a placenta.

pea-kay

i'm guessing the person who asked was wondering if they're di/di, di/mo, or mo/mo. meaning,

two gestational sacs? one gestational sac and two amniotic sacs? or one gestational sac and one amniotic sac? 

or, are they sharing a placenta or not?

if they're ID, they're definitely the same gender. if they're fraternal, obviously they can be the same or different.

jls7284

from the u/s picutre i took home it looks like they are in separate sacs, but the ob didnt say anything about it. i am kind of upset that he didnt tell me if they are identical or not, is it possible that he couldnt tell yet? (i am 10 weeks)

jacobandcrystal

If it is obvious to you that they're in separate sacs... and if there is a very thick wall between them, it sounds like they are probably fraternal.

Temp159135562506975

depending on when the egg splits, you can have 2 sacs with ID's... so sometimes you can't know if they are ID/fraternal until they are born - and DNA tested - unless of course, they are boy/girl... or if their blood type is different at birth (which my boys are).  

 You will hear that there CAN be boy/girl ID twins- but it's SOOOO rare, that it's not really considered when talking about IDs or not.

 

 

Laura Emerick

There are only identical and fraternal.  Identical twins come from one fertilized egg that splits into two embryos.  Fraternal twins occur when 2 eggs are simultaneously fertilized by 2 separate sperm.

Boy/girl twins are always fraternal. Same-sex twins can be fraternal or identical.  Identical twins share the same genes, hence they would never be of opposite sexes.

It is sometimes impossible to tell which type of twins you have until examination of the placenta after birth.  The doctor does this, or it is sent to the lab to be analysed.  For example, my twins each have their own placentas and their owns sacs.  Therefore they are probably fraternal, but they still may be identical.  The sharing (or separate) placentas and/or sacs in identical twins is determined by the # of days following conception that the fertilized egg split.

Your questions are not stupid. I didn't understand the di-di stuff (you can google it, too) until I read that section of "When You're Expecting Twins, Triplets or Quads."  That's got some great info.

Hope that helps!

jacobandcrystal

Here's a Wikipedia article that I found helpful when we first found out : )

https://en.wikipedia.org/wiki/Twin

Mom of 2+2=4

Previous posters have answered your questions, so I just want to say....Congratulations on your twin pregnancy!!