I work in a Blood Bank --
I'm sure your friend's baby's physician knows why this is happening.
1.) Was the mother's blood type compatible with the baby's -- not just Rh positive or negative.
2.) Is the baby bleeding internally somewhere?
Your friend needs to ask the doctor. He should have an answer and should have some sort of idea of how long transfusions need to be given.
What you can do, and all of her friends, is go give blood -- you can give donor directed blood (if you're the same type as the baby!) It's tested just the same as though it was being given to a stranger. The nicest part of giving blood to a baby is that it is a much smaller amount!
I agree with Chasity (your second response). However, I believe Idopathic Thrombocytopenia Purpura (ITP) -- or something like that -- only receives platelets. Tell her to ask for a Hemotologist .... especially if he "doesn't know" for sure!