How precise, how meaningful are medicine's definitions? A baby, Eugene Field once announced, "... is composed of a bald head and a pair of lungs." Although this definition may suffice for literature, science demands more precision. And our previous definitions, Sinclair1 claims, no longer are adequate, if indeed they ever were. The minimal and maximal criteria which bracket those youngsters we call "babies" are too widely separated.
If we define a newborn infant as one weighing between 1,500 and 4,500 gm, for example, we have established a range almost equivalent to that separating the child and the adult. "It would seem as inappropriate [Sinclair suggests] for the small and large neonate to be included together in experimental studies under the label 'baby,' as for the baby, child, and adolescent to be grouped with the adult under the heading 'people.' " This kind of grouping may occasionally result in administration of inappropriate
WHEN IS A BABY?. JAMA. 1967;200(3):245. doi:10.1001/jama.1967.03120160111020