I recently had my first baby, who came out a little premature. I was disgusted by the sheer volume of blood testing performed. The NICU staff did the normal, government-mandated tests, then they did regular blood testing every week to monitor her anemia. Somehow the NICU staff was "mystified" as to why my daughter's anemia was getting worse. I'm not a doctor. I am an engineer on a campus with medical journal access. With a simple model based on her estimated blood volume and the volume they removed for all the tests, I postulate that it was their excessive testing that put my daughter in the danger zone of anemia. Had they just left my daughter alone, I think she would have had the typical levels of Hematicrit and Hemoglobin. I think this dangerous, excessive testing was defensive medicine.
Diagnostic testing is specifically mentioned in many journal articles on infant anemia.