The World Health Organization child growth standards: expected implications for clinical and epidemiological research.

In 2006 and 2007, the World Health Organization (WHO) released two sets of child growth standards (World Health Organization, WHO Child Growth Standards. Methods and development. Length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age. WHO, Geneva, 2006; World Health Organization, WHO Child Growth Standards: Methods and Development. Head circumference-for-age, arm circumference-for-age, triceps skinfold-for-age and subscapular skinfold-for-age. WHO, Geneva, 2007) to replace the National Center for Health Statistics references (Hamill et al., National Center for Health Statistics, Vital and Health Statistics Series 11, No 165, 1977) as an international tool for growth and nutritional assessment. This paper explores the scope of implications for future anthropometric research, highlighting foreseeable effects on the choice of research questions, choice of nutritional indices, training of measurers, and issues of internal and external validity of research results. The conclusion drawn is that the introduction of the WHO child growth standards is expected to have wide implications for growth and nutrition research. The full scope of this effect will gradually become clear while researchers, similar to health care workers, make the transition to using the new standards, re-evaluate results of past approaches, and explore the uses and functional validity of the standards, including those for indices that were not previously available.