No growth chart has resolved what to do with the physiologic postnatal weight loss when extracellular water is decreased. Nevertheless, the Fenton Growth Chart provides the most comprehensive comparison to the current growth standard for the preterm infant particularly with growth after return to birthweight. Existing postnatal growth references have limitations since they are based on less than ideal samples, and do not provide guidance about the importance of any deviations from the mean of the reference samples. Errors in length measurement have been found to be evenly distributed as under and overestimations, and therefore are unlikely to introduce bias.