Why are the WHO Charts Needed?

The US Center for Disease Control and Prevention (CDC) recommends using the World Health Organization (WHO 2006) growth charts to monitor growth for all children less than two years and the CDC (2000) growth charts for children two years and over.

The WHO charts are described as 'optimal' rather than 'average' growth and are based on:

  • healthy, term babies
  • exclusive breastfeeding at least four months
  • introduction of solids by six months and continued breastfeeding for a year
  • non-smoking mothers
  • not low socio-economic status
  • data collection from birth to five years
  • similar growth patterns in children from the six countries (USA, Norway, India, Ghana, Brazil, Oman).

WHO promotes these charts for children from all ethnic backgrounds, irrespective of the type of infant feeding.

The previous charts (CDC) were based on health surveys in the US between 1963 and 1994.
Criticisms of these charts are:

  • less than half the mothers initiated breastfeeding
  • small sample size
  • skewed towards higher weight because of increasing rates of obesity.

These charts are now recommended for children aged two years and over.

Difference between CDC and WHO growth charts 0-2 years

Weight: Differences in weight for age curves are most marked in infancy. Children in the WHO charts grow faster and have higher mean weights than the CDC children in the first few months of infancy. At around six months the lines cross and children in the WHO study are on average lighter than the CDC children from 6-32 months after which the medians are similar to 60 months.

Length: Length or height for age show similar shaped curves. On average WHO children are slightly taller than the CDC children. The WHO curves have much tighter variability and slower growth rates would be higher for all age groups using the WHO charts.

Weight for length and weight for height The CDC children are on average heavier, so rates of overweight are higher when using the WHO standard, and rates of underweight are lower.

BMI The BMI curves are higher on the CDC charts compared with the WHO charts. This reflects the higher prevalence of overweight children in the CDC sample, compared with the WHO charts.

Activities: Illustration of key differences between CDC and WHO charts

Activity A

Plotting of growth patterns may vary depending on what growth chart is used.  

Figure A.1 shows the weight gain for a boy at the 50th centile on the CDC chart. His weights are: 3.6 kg at birth, 4.4 kg at one month, 5.3 kg at two months and 6.7 kg at four months.

Figure A.2 shows the same weights plotted on the WHO chart. On the WHO chart, the 50th centile weight at four months is approximately 7 kg.

This example shows that the growth pattern on the WHO chart is close to the CDC chart, although by four months, growth appears slightly 'slower' on the WHO chart compared to the CDC chart.

There may be concerns that some exclusively breastfed babies may be perceived to show 'poor' growth in the first 4-6 months. Nurses need to reassure parents that this growth is normal and healthy, and continue to support mothers to breastfeed.

Figure A.1 and Figure A.2 - visual representation of the previous paragraphs 

Figure A.1 CDC birth to 36 months weight for age, boy
Source: Developed by the National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion (2000).
Figure A.2 WHO birth to 24 months weight for age, boy
Source: World Health Organisation Child Growth Standards

Activity B

Plotting of growth patterns may vary depending on what growth chart is used.  

Figure B.1 shows the weight gain for a boy growing along the 90th centile on the CDC chart. His weights are: 10.4 kg at eight months, 11.9 kg at 12 months, 13.5 kg at 18 months and 14.6 kg at two years.

Figure B.2 shows the same weights plotted on the WHO chart. On the WHO chart, the 90th centile weight at 24 months is approximately 14 kg. This child now appears 'bigger' on the WHO chart compared to the CDC chart.

This activity shows that some children may appear 'heavier' on the WHO chart compared to the CDC chart. Growth assessment should always take into account previous weight together with length / height measurements, the overall health and wellbeing of the child, family factors and other influences on child growth.

Figure B.1 and Figure B.2 - visual representation of the previous paragraphs 

Figure B.1 CDC birth to three years weight for age, boy
Source: Developed by the National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion (2000).
Figure B.2 WHO birth to 24 months weight for age, boy
Source: World Health Organisation Child Growth Standards

Activity C

Plotting of growth patterns may vary depending on what growth chart is used.  

Figure C.1 shows the length of a boy (88 cm) at 24 months plotted on the WHO length chart on the 50th centile.

Figure C.2 shows the same measurement plotted as 'height' on the CDC chart. There is no appreciable difference in the changeover from WHO to CDC chart at two years of age. In practice, length measurement is up to 2 cm more than height /stature measurement.

Figure C.1 and Figure C.2 - visual representation of the previous paragraphs 

Figure C.1 WHO birth to 24 months length for age, boy
Source: Developed by the National Center for Health Statistics in collaboration with the National Center for Chronic Disease Prevention and Health Promotion (2000).
Figure C.2 CDC 2 to 18 year old height for age, boy
Source: World Health Organisation Child Growth Standards