If you have spent time beside an incubator in a neonatal intensive care unit (NICU), you may have heard the word transfusion more than once. Babies born very early and very small — under about two pounds, or 1,000 grams — almost always become anemic, meaning they run low on red blood cells. Red…

A large international study followed premature babies who had low platelet counts and found that giving platelet transfusions more freely did not help them and actually caused harm that lasted into early childhood. Babies given transfusions at a more generous threshold were more likely to have died or to have a developmental problem by age two than babies given them only when their counts fell much lower. The clear lesson: for these infants, a more cautious, "wait-and-watch" approach is safer.