Children aged under 5 years who are underweight

Percent of children aged under 5 years whose weight-for-age is below -2 standard deviations of the WHO Child Growth Standards median.

Number of children aged 0–59 months who are underweight.

Total number of children aged 0–59 months who were measured.

Place of residence, age, sex, socioeconomic status.

WHO maintains the Global Database on Child Growth and Malnutrition, which includes population-based surveys that fulfil a set of criteria. Data are checked for validity and consistency and raw data-sets are analysed according to a standard procedure to obtain comparable results. Prevalence below and above defined cut-off points for weight-for-age, height-for-age, weight-for-height and body mass index (BMI)-for-age in pre-school children are presented using z-scores based on the WHO Child Growth Standards. Predominant type of statistics: adjusted.

Population-based household surveys.

Population-based health surveys with nutrition modules, national surveillance systems.

Child growth is internationally recognized as an important indicator of nutritional status and health in populations. As weight is easy to measure, this is the indicator for which most data have been collected in the past. Evidence has shown that the mortality risk of children who are even mildly underweight is increased, and severely underweight children are at even greater risk. Thus, monitoring weight-for-age can help assess the contribution of growth promotion programs to mortality reduction. 

Weight-for-age reflects body mass relative to chronological age. Low weight-for-age identifies the condition of being light or underweight for a specific age and reflects the process of gaining insufficient weight relative to age or losing weight. Since weight-for-age is influenced by both the height of the child and by its weight, the indicator reflects both past (chronic) and/or present (acute) undernutrition. This indicator is also a measure of health and nutritional risk in a population.

Underweight, based on weight-for-age, is recommended as the indicator to assess changes in the magnitude of malnutrition over time.

The percentage of children who have low weight for age (underweight) can reflect ‘wasting’ (i.e. low weight for height), indicating acute weight loss, ‘stunting’, or both. Thus, 'underweight' is a composite indicator and may therefore be difficult to interpret.

One of the major limitations of the indicator is the issue of the reliability of weight measurements. There may be some degree of variability between interviewers in performing the task of weighing. For weight, the largest acceptable difference between repeated measurements is 0.5 kg (Cogill, 2003). Enumerator variability in weight measurement can be reduced through extensive training. The validity of this indicator also depends on the accuracy of the weighing instruments and the caretaker’s ability to report the correct age of the child.

Pediatric care, Nutrition, Child health, Morbidity

World Health Organization (WHO). 2015 Global Reference List of 100 Core Health Indicators.; 2015.

World Health Organization. Nutrition Landscape Information System (NLIS). Country Profile Indicators: Interpretation Guide. Geneva, Switzerland; 2010.

WHO. WHO Global Database on Child Growth and Malnutrition. Department of Nutrition for Health and Development (NHD), Geneva, Switzerland.

Gage AJ, Ali D, Suzuki C. A Guide for Monitoring and Evaluating Child Health Programs. MEASURE Evaluation. Carolina Population Center, University of North Carolina at Chapel Hill.; 2005.