Assessment of growth: variations according to references and growth parameters used.

Numerous studies have investigated associations between early growth and future risk of obesity, but the methods used varied considerably. Different growth references or parameters can be considered. Growth references from France, the United States (the Centers for Disease Control and Prevention), the Netherlands, Belgium, and the United Kingdom were compared with World Health Organization (WHO) standards. For the first 3 mo of life, all references showed markedly lower values for weight, length, and body mass index (BMI) compared with WHO standards, but after the age of 6 mo references were generally higher than WHO standards. Compared with nonbreastfed infants, the growth of breastfed infants was generally closer to that of WHO standards. Because data in the WHO standards were collected on infants who were breastfed, the difference between references and WHO standards might be mainly attributable to feeding practices. Epidemiologic and clinical studies evaluated the consequences of using either WHO standards or national references and showed differences according to the reference used. Analyses of children's weight curves by physicians showed significant differences in the interpretation of child growth and therefore in the advice given to parents. Finally, the effect of using different growth parameters to predict future risk of obesity was examined and showed that weight and length gains may be good candidates to study future risks. In conclusion, because the reference or parameters used to assess growth have an important effect on the interpretation of growth, it is crucial to be aware of the consequences of the methods used in clinical or epidemiologic contexts.