The issue raised in Needleman's commentary (Pediatrics 68:894, 1981) is the interpretation of two studies in an area in which methodologic concerns are paramount. We appreciate the pioneering efforts in the studies that preceded the Boston study1 and our current paper2; from these published reports and informal exchange of material all of us have learned much that guides more sophisticated endeavor. Two recent objective reviews3,4 describe some, but not all, of the design problems pertaining to the earlier works.