Binns et al1 in the August 1996 Archives show that a cohort of Chicago-area children were heavier at birth and throughout the first 6 months of life compared with the cohort measured for the current standard curves, generated by the National Center for Health Statistics (NCHS) and in use since 1977.2 Their study correctly highlights the need to ensure that our "standards" are still appropriate.
The differences in growth curves noted in this study raise an unresolved issue: pediatricians should reflect on what we wish to consider "normal" human growth patterns before generating new standardized growth curves. The authors mention that the "majority of infants" in their study "were breast-fed," while the infants in the NCHS cohort were mostly formula-fed. This difference in feeding does provide a possible explanation for some of the variation between the populations, since a US study involving exclusively breast-fed infants3 has found that
Basco WT. Choose Standards for Infant Growth Wisely. Arch Pediatr Adolesc Med. 1997;151(3):322. doi:10.1001/archpedi.1997.02170400108022