Amber informend me that I needed to explain how we know which twin is which. As far as the medical people go, the twins are "baby A" and "baby B." Twins come in all kinds of different combinations as far as how they are positioned int he womb. Ours are in separate sacs but share a placent. At the very beginning of our checkups, the ultrasound technician found which sac was positioned closer to the cervix. That twin is thereafter labeled "Baby A" because unless something goes wrong, she will be born first. The baby further away from the cerviz then becomes "Baby B." I'm not entirely sure how Amber decided which was which once we go tot that point other than she always thought of the low kics as Sophie's and the kicks in her ribs as Mattie's. So that is how we know which twin is which.
Incidentally, we're pretty sure now the girls are identical. From what I've studied, Twin to Twin Transfusion almost always happens in identical twins.... So the question of "how do you know which twin is which?" is probably easier to answer now than it will be for the rest of their lives? We're thinking about tattoing "A" and "B" on their foreheads just for old times sake. :)