Interpreting Growth Indicators Using the WHO Growth Charts

There are differences in the prevalence of growth indicators when using the WHO growth charts compared to the CDC growth charts.

A comparison of low length-for-age, weight-for-age and weight-for-length, and high weight-for-length in US children among infants and children up to 24 months of age using the 2006 WHO growth standard charts and the 2000 CDC growth reference charts (comparing the 2.3^rd and 97.7^th percentiles for the WHO growth charts and 5^th and 95^th percentiles for the CDC growth charts) shows that prevalence of nutritional status indicators are as follows.  

• Low length-for-age: The prevalence of low-length-for-age is very similar (within 0.25 percentage points)¹ on the WHO and the CDC growth charts.
  
• Low weight-for-age: In the first two years of life, the prevalence of low weight-for-age is generally lower on the WHO charts compared to the CDC 2000 charts except in the first 5 months of life when it is similar on both charts.¹ This may be beneficial because over-diagnosis of low weight-for-age can result in unnecessary interventions and possibly damage the parent-child interaction.²  Children identified as having low weight-for-age on the WHO growth charts will be more likely to have a true weight deficiency that requires follow up.³
    See WHO Boys Weight-for-age Percentiles Birth to 24 Months compared to CDC Boys Weight-for-age Percentiles Birth to 24 Months).
  
• Low and high weight-for-length: The prevalence of low weight-for-length is about 3 percentage points lower on the WHO charts compared to the CDC charts.¹ The prevalence of high weight-for-length is generally lower on the WHO charts compared to the CDC charts.¹
  For a comparison of the WHO and CDC growth chart prevalences of low length-for-age, low weight-for-age, and high weight-for-length among children aged < 24 month---United States, see Use of World Health Organization and CDC Growth Charts for Children Aged 0–59 Months in the United States [PDF-780KB] MMWR 2010.³

References

¹Mei Z, Ogden CL, Flegal KM, Grummer-Strawn LM. Comparison of the prevalence of shortness, underweight, and overweight among US children aged 0 to 59 months by using the CDC 2000 and the WHO 2006 growth charts. J Pediatr 2008;153(5):622-628.

²Wright JA, Ashenburg CA, Whitaker RC. Comparison of methods to categorize undernutrition in chidren. J Pediatr 1994;124(6):944-6.

³Grummer-Strawn LM, Reinold C, Krebs NF; Centers for Disease Control and Prevention (CDC). Use of the World Health Organization and CDC growth charts for children aged 0-59 months in the United States. Recommendations and Reports. MMWR Recomm Rep 2010; 59(RR-9);1-15.