If non-Group O red cells are transfused, verify that there isn't demonstrating anti-A, anti-B or anti-A,B in the baby. Test reverse cells through Coombs phase or crossmatch the red cell unit. To avoid the need to do this testing, transfuse Group O, Rh compatible red cells.
In my experience, it's best to limit donor exposure to the infant, if possible, for small volume transfusions. Most facilities I have worked in dedicate a unit to the neonate from the first transfusion request until the unit expires or is used up. CPDA or AS-, AS3 anticoagulant preferred - the fresher the unit when assigning to the baby, the longer it will last. We also only assigned 2 babies per unit and aliquoted the desired volume from the original bag with each transfusion request as close as possible to the time of transfusion. We only irradiated the aliquot ,not the original bag to avoid an increase in extracellular potassium that occurs after irradiation with storage.