WHO Growth Standards Are Recommended for Use in the U.S. for Infants and Children 0 to 2 Years of Age
The World Health Organization (WHO) released a new international growth standard statistical distribution in 2006, which describes the growth of children ages 0 to 59 months living in environments believed to support what WHO researchers view as optimal growth of children in six countries throughout the world, including the U.S. The distribution shows how infants and young children grow under these conditions, rather than how they do grow in environments that may not support optimal growth.
Why use WHO growth standards for infants and children ages 0 to 2 years of age in the U.S?
- The WHO standards establish growth of the breastfed infant as the norm for growth.Breastfeeding is the recommended standard for infant feeding. The WHO charts reflect growth patterns among children who were predominantly breastfed for at least 4 months and still breastfeeding at 12 months.
- The WHO standards provide a better description of physiological growth in infancy.Clinicians often use the CDC growth charts as standards on how young children should grow. However the CDC growth charts are references; they identify how typical children in the US did grow during a specific time period. Typical growth patterns may not be ideal growth patterns. The WHO growth charts are standards; they identify how children should grow when provided optimal conditions.
- The WHO standards are based on a high-quality study designed explicitly for creating growth charts.The WHO standards were constructed using longitudinal length and weight data measured at frequent intervals. For the CDC growth charts, weight data were not available between birth and 3 months of age and the sample sizes were small for sex and age groups during the first 6 months of age.
Downloadable PDFs of Growth Charts:
- GIRLS: Birth to 24 Months: Length-for-age and Weight-for-age percentiles
- GIRLS: Birth to 24 Months: Head circumference-for-age and Weight-for-length percentiles
- BOYS: Birth to 24 Months: Length-for-age and Weight-for-age percentiles
- BOYS: Birth to 24 Months: Head circumference-for-age and Weight-for-length percentiles
How different are the new standards from the old growth charts?
The new standards differ from any existing growth charts in a number of innovative ways. First the MGRS was designed to provide data that describe “how children should grow,” by including in the study’s selection criteria specific health behaviors that are consistent with current health promotion recommendations (e.g., breastfeeding norms, standard pediatric care, non-smoking requirements). This new approach is fundamentally different from that taken by the traditional descriptive references. By adopting a prescriptive approach, the protocol’s design went beyond an update of how children in presumably healthy populations grow at a specific time and place and explicitly recognizes the need for standards (i.e., devices that enable value judgments by incorporating norms or targets in their construction). Arguably, the current obesity epidemic in many developed countries would have been detectable earlier if a prescriptive international standard had been available 20 years ago.
Another key characteristic of the new standard is that it makes breastfeeding the biological “norm” and establishes the breastfed infant as the normative growth model. The previous reference was based on the growth of artificially-fed children.
The pooled sample from the 6 participating countries will allow the development of a truly international standard (in contrast to the previous international reference based on children from a single country) and reiterate the fact that child populations grow similarly across the world’s major regions when their needs for health and care are met.
These standards also include new innovative growth indicators beyond height and weight that are particularly useful for monitoring the increasing epidemic of childhood obesity, such as the skinfold thicknessess.
The study’s longitudinal nature will also allow the development of growth velocity standards. Health care providers will not have to wait until children cross an attained growth threshold to make the diagnosis of under-nutrition and overweight since velocity standards will enable the early identification of children in the process of becoming under- or over-nourished.
Lastly, the development of accompanying windows of achievement for six key motor development milestones will provide a unique link between physical growth and motor development.