Malnutrition contributes to about one-third of the 9.7 million child deaths that occur each year. (1,2) Recently, the World Health Organization (WHO) introduced new child growth standards for use in deriving indicators of nutritional status, such as stunting, wasting and underweight. These standards are based on the growth of infants from six different regions of the world who were fed according to WHO and United Nations Children's Fund (UNICEF) feeding recommendations, had a non-smoking mother, had access to primary health care and did not have any serious constraints on health during infancy or early childhood. (3-6) It is recommended that these new growth standards replace the previously recommended international growth reference devised by the National Center for Health Statistics (NCHS) in the United States. (7)
The prevalence of malnutrition estimated using WHO standards is expected to differ from that based on the NCHS growth reference because there are differences in median weight-for-age, height-for-age and weight-for-height between the two. (8) Recent studies have investigated the direction and magnitude of these differences. (9-12) In children aged 6-59 months, the prevalence of stunting (i.e. low height-for-age) and wasting (i.e. low weight-for-height) were higher when WHO standards were used but that of underweight (i.e. low weight-for-age) was lower. (9,11,12) In the first half of infancy (i.e. the period from birth up to the end of the 6th month), the prevalence of stunting, wasting and underweight has been reported to be higher with WHO growth standards. (10,12) It is important that the magnitude of these apparent changes in the prevalence of malnutrition are investigated in different settings in order to gain a better understanding of their implications, particularly for child health and nutrition programmes whose progress is monitored through large household surveys.
Another important question connected with growth in the first 6 months of life is its relationship with feeding practices. Exclusive breastfeeding is recommended for infants up to 6 months of age because of its benefits in reducing morbidity and mortality. (13) In their systematic review of the optimal duration of exclusive breastfeeding, Kramer and Kakuma (14) combined the results of two studies conducted in Honduras and found that exclusively breastfed infants had a lower prevalence of stunting, wasting and underweight, although not significantly so.
Malnourished children are known to be at an increased risk of death. (15-20) Nutritional status indicators can be used to identify those infants and children at a higher risk of dying so they can be provided with special care both at a population level in emergency settings and individually following screening. For example, low weight-for-age is used in the UNICEF-WHO Integrated Management of Childhood Illness (IMCI) programme to identify infants whose feeding practices should be assessed and who would benefit from additional counselling on infant feeding. (21) It is not yet known whether nutritional status assessed using WHO growth standards or the NCHS growth reference would be a better predictor of death, and answering this question has been proposed as a research priori. (12,22)
We carried out a secondary analysis of a large data set obtained from a randomized controlled trial of vitamin A supplementation conducted in Ghana, India and Peru (23) to determine how using the NCHS growth reference or WHO growth standards influences the calculated prevalence of malnutrition, the relationship between exclusive breastfeeding and malnutrition, and the sensitivity and specificity of nutritional status indicators for predicting the risk of death during infancy.
Between 1995 and 1997, 9424 mother--infant pairs were enrolled in a randomized controlled trial of vitamin A supplementation linked to the WHO Expanded Programme on Immunization (EPI): 2919 mother--infant pairs were from 37 villages in the Kintampo district of Ghana, 4000 were from two urban slums in New Delhi, India, and 2505 were from a periurban shanty town in Lima, Peru. …