Growth & Development: WHO Growth Standards

Recommendations from the WHO Working Group on Infant Growth

A multinational study, the WHO Multicentre Growth Reference Study evaluated the growth of infants and children from birth to 5 years of age in:

• Pelotas, Brazil
• Accra, Ghana
• Oslo, Norway
• New Dehli, India
• Muscat, Oman
• Davis, California, USA

Mothers and infants were visited at birth, and 1743 were enrolled at 2 weeks of age. Families were visited at home 21 times up until the child was 2 years of age. Criteria for enrollment included term single birth, no health, environmental or economic constraints on growth and a non smoking mother. The mothers had to be willing to follow the feeding plan of exclusive or predominant breastfeeding up to 4 months of age with the addition of complementary foods by 6 months of age and continued breastfeeding until 12 months of age ( WHO Multicentre Growth, 2004 ). 888 mother-infant pairs were followed until 24 months of age and completed the study ( WHO Multicentre Growth, 2006-1 ). With the exception of the mothers in Pelotas, Brazil, over 60% of enrolled mothers were exclusively or predominately breastfeeding when their baby was 4 months of age and were still breastfeeding when their infant was 1 year of age ( WHO Multicentre Growth, 2006-2 ).

Data on the growth of children aged 24-71 months of age were collected with cross-sectional sampling in the same locations used to collect the longitudinal sample. Children were recruited whose mothers gave a history of breastfeeding until at least 1 year of age with the addition of complementary foods by 6 months of age. They attempted to enroll 70 children at each site for each 3 month age interval from 18-71 months. They enrolled 6697 children. The characteristics of the children were:

• average duration of any breastfeeding - 14.3 months
• average age of introduction of complementary foods - 4.9 months
• average age when formula or milk was started - 7.6 months ( WHO Child Growth Standards, 2006 ).

The major finding of the study was that there was a greater difference in growth among children in a single site than among children at the different sites. So when maternal nutrition, and environment do not limit children's growth and infants are fed optimally according to WHO recommendations, infants and children of different racial and ethnic groups grow similarly ( WHO Multicentre Growth, 2006-3 ).

de Onis and coworkers compared the WHO growth standards to the CDC 2000 growth curves presently in use in the US. From 2 months to 6 months of age the infants in WHO growth standards have a higher mean weight and from 6 months to 12 months they have a lower mean weight. This is related to the larger sample size in the WHO sample and to the differences in weight gain in the first year of life in breast infants compared to formula fed infants. The length/height of infants and children in the WHO sample are slightly taller than those in the CDC sample ( de Onis, 2007 ).

The WHO Growth Standards and information on the study implementation and data analysis are available on the WHO website ( WHO Growth Standards, 2008 ).

In September of 2010, the CDC recommended the use of the new WHO Growth Standards for monitoring the growth of all infants and toddlers in the United States between birth and 24 months of age. Using these growth curves to monitor the growth of breastfed infants in the first 2 years of life should prevent the appearance that breastfed infants are not following growth curves between the ages of 6 -12 months of age (CDC-WHO Growth Charts, MMWR, 2010 ).