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Updated: May 3, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Extending World Health Organization weight-for-age reference curves to older children
Celia Rodd1, Daniel L Metzger, Atul Sharma
1Section of Pediatric Endocrinology, Children's Hospital of Winnipeg, FW 302-685 William Ave, Winnipeg, MB R3E 0Z2, Canada. crodd@hsc.mb.ca.
Insights
This study extends weight-for-age reference curves for children aged 10-19 years, addressing concerns about the omission of weight data in older children. The revised charts offer more precise growth assessments and reduce misclassification risks.
Area of Science:
- Pediatric growth monitoring
- Biostatistics
- Public health surveillance
Background:
- World Health Organization (WHO) growth charts for ages 5-19 are based on 1963-75 US National Center for Health Statistics (NCHS) data.
- Weight-for-age data was omitted for ages >10 years in WHO charts, raising concerns among health providers.
- This study addresses the need for extended weight-for-age reference curves in older children and adolescents.
Purpose of the Study:
- To extend weight-for-age reference curves from 10 to 19 years using existing NCHS core data.
- To revise displayed centiles for improved clinical utility.
- To enhance the assessment of normal and aberrant growth in older children.
Main Methods:
- Applied WHO exclusion criteria to the NCHS core data to create a "non-obese sample with equal height".
- Utilized optimal Box-Cox power exponential models to fit smoothed weight-for-age centiles.
- Employed bootstrap resampling for precision assessment and included additional centiles in the healthy range (3-97%).
Main Results:
- Extended weight-for-age charts are now available for children aged 10-19 years.
- The revised charts offer greater granularity within the healthy growth range (3-97%).
- Extreme centiles (0.1% and 99.9%) were removed, reducing the risk of misclassification.
Conclusions:
- The new charts complement existing WHO charts, enabling concurrent plotting of weight-for-age and height in older children.
- Modifications adhere to WHO methodology and use the same NCHS core data.
- Enhanced centiles facilitate precise growth assessment and earlier detection of growth deviations.
Background:
For ages 5-19 years, the World Health Organization (WHO) publishes reference charts based on 'core data' from the US National Center for Health Statistics (NCHS), collected from 1963-75 on 22,917 US children. To promote the use of body mass index in older children, weight-for-age was omitted after age 10. Health providers have subsequently expressed concerns about this omission and the selection of centiles. We therefore sought to extend weight-for-age reference curves from 10 to 19 years by applying WHO exclusion criteria and curve fitting methods to the core NCHS data and to revise the choice of displayed centiles.
Methods:
WHO analysts first excluded ~ 3% of their reference population in order to achieve a "non-obese sample with equal height". Based on these exclusion criteria, 314 girls and 304 boys were first omitted for 'unhealthy' weights-for-height. By applying WHO global deviance and information criteria, optimal Box-Cox power exponential models were used to fit smoothed weight-for-age centiles. Bootstrap resampling was used to assess the precision of centile estimates. For all charts, additional centiles were included in the healthy range (3 to 97%), and the more extreme WHO centiles 0.1 and 99.9% were dropped.
Results:
In addition to weight-for-age beyond 10 years, our charts provide more granularity in the centiles in the healthy range -2 to +2 SD (3-97%). For both weight and BMI, the bootstrap confidence intervals for the 99.9th centile were at least an order of magnitude wider than the corresponding 50th centile values.
Conclusions:
These charts complement existing WHO charts by allowing weight-for-age to be plotted concurrently with height in older children. All modifications followed strict WHO methodology and utilized the same core data from the US NCHS. The additional centiles permit a more precise assessment of normal growth and earlier detection of aberrant growth as it crosses centiles. Elimination of extreme centiles reduces the risk of misclassification. A complete set of charts is available at the CPEG web site (http://cpeg-gcep.net).
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