Let see, Identical Twins happen when only one egg is fertilized by one sperm (like a "normal" pregnancy) but for some unknown reason, that fertilized egg splits to form two complete babies with the same DNA, so yes, both will be the same sex. Fraternal Twins are the result of two eggs each getting fertilized by different sperm, basically, 2 complete, seperate babies, just like regular brothers and sisters. Fraternal twins can be the same sex or different sexes and do not have the same dna.
They can pretty much tell right away because when you look at the ultrasound, you see one big sac, which is called the corion (sp?) or placenta but inside that one sac, there are two babies. They are pretty sure my babies are each in there own amniotic sac, which is a very good thing. Babies sharing both a placenta and amniotic sac are very difficult to carry to term and usually have many more complications.
Fraternal twins are thought to be partially genectic, meaning they can run in families. Or, a lot of the time they happened because fertility drugs make you produce more than one egg. Evne though I was on fertility drugs, it has nothing to do with the kind of twins I'm carrying. They don't know why some fertilized eggs split and make two babies, its basically a fluke of nature!! A mighty good fluke if you ask me!!!
Identical twins are higher risk than fraternal twins because of the shared placenta. They are at risk of TTTS, twin-twin tranfusion syndrome and a list of other things. I don't completley understand this yet but it has something to do with one twin kind of hogging the blood supply. Some how blood vessels connect between the babies and there blood flows through eachother but only one of the babies hearts is actually pumping the blood. The mortality rate is very high, about 80%. I've never heard of this before today so I'm sure thats not the best explanation.
At this point, I'm just going with the happy news and figure we will deal with issues as they arise. I'm hoping the RE can get me into the special high risk group of dr's and hopefully they can give me some more answers!
-------------------- Taking it one day at a time.....