Twin terminology - what does it all mean ?

Twin Terminology

There are 3 main reference points which you may hear a lot of from now on in. They include the chorion (placenta), the amnion (the sac containing fluid in which the baby grows) and the zygosity (referring to the egg). These terms refer to whether the babies have their own amniotic sac, their own chorion (placenta) and whether they came from one egg or two.

A prefix of mono means one, so monochorionic means one placenta, diamniotic means 2 amniotic ....