Children (<5 years) who are overweight

Number of children under 5 years of age falling above 2 standard deviations (moderate and severe) from the median weight-for-height of the reference population​

Children under 5 years of age in the surveyed population​ with valid weight-for-height​​ z-scores​

WHO Child Growth Standards 2006

Children 0-59 months

Modelled

Chika Hayashi

[email protected]

Child growth is an internationally accepted outcome area reflecting child nutritional status. Child overweight refers to a child who is too heavy for his or her height. This form of malnutrition results from expending too few calories for the amount of food consumed and increases the risk of noncommunicable diseases later in life. Child overweight is one of the World Health Assembly nutrition target indicators.

The official MDG indicator is overweight as assessed using weight-for-height. Overweight can however also be assessed with other indicators such body mass index (BMI)-for-age. In general BMI-for-age is not used in the joint dataset but has been considered in absence of any other available estimates.

Survey estimates come with levels of uncertainty due to both sampling error and non-sampling error (e.g. measurement technical error, recording error etc.,). None of the two sources of errors have been fully taken into account for deriving estimates neither at country nor at regional and global levels. Of particular concern for overweight is the fact that data for high income countries are scarce yet the rates are generally higher among the high income countries with data and so the lack of representation from high income countries may affect the global and even regional rates

Survey estimates are based on standardized methodology using the WHO Child Growth Standards as described elsewhere (Ref: Anthro software manual). Global and regional estimates are based on methodology outlined in UNICEF-WHO-The World Bank: Joint child malnutrition estimates – Levels and trends (UNICEF/WHO/WB 2012)

Global and regional estimates refer to the age group of children under 5 years, sexes combined. Disaggregated country data are available in a majority of household surveys and UNICEF – WHO- The World Bank Group have expanded the joint data set to include sub national and stratified estimates (e.g. sex, age groups, wealth, mothers’ education, residence) which was released in 2018.

No imputation methodology is applied to derive estimates for countries or years where no data is avaialble.

Countries and years are treated as missing randomly following a multilevel modeling approach (3).

Regional aggregates are available for the following classifications: UN, MDG, UNICEF, WHO, The World Bank regions and income groups.

The standard analysis approach to construct the joint data set aims for a maximum comparability of country estimates. For the inclusion of survey estimates into the JME dataset, the inter-agency group applies survey quality assessment criteria. When there is insufficient documentation, the survey is not included until information becomes available. When raw data are available, and there is a question about the analysis approach, data re-analysis is performed following the standard methodology (1). Discrepancies between results from the standardised approach and those reported may occur for various reasons, for example, the use of different standards for z-score calculations, imputation of the day of birth when missing, the use of rounded age in months, the use of different flagging systems for data exclusion. For surveys based on the previous NCHS/WHO references, and for which raw data are not available, a method for converting the z-scores to be based on the WHO Child Growth Standards is applied (4). In addition, when surveys do not cover the age interval 0-<5 years, or are only representative of the rural areas, an adjustment based on other surveys for the same country, is performed. Any adjustment or conversion is transparently stated in the annotated joint data set.

More than 150 countries.

At country level, data are provided for the years where surveys are included in the joint dataset. Survey years begin in 1983. For the global and regional levels, annual estimates are available between 1990 and the latest available estimate upon release each year (i.e. in Sept 2016 edition of the Joint Malnutrition Estimates the latest available estimate was for 2015).

For the majority of countries, nationally representative household surveys constitute the data source. For a limited number of countries data from surveillance systems is used if sufficient population coverage is documented (about 80%). For both data sources, the child’s height and weight measurements have to be collected following recommended standard measuring techniques (1).

UNICEF, WHO and the World Bank group jointly review new data sources to update the country level estimates. Each agency uses their existing mechanisms for obtaining data.

For WHO, see published database methodology (de Onis et al. 2004). For UNICEF, the cadre of dedicated data and monitoring specialists working at national, regional and international levels in 190 countries routinely provide technical support for the collection and analysis of data. For the past 20 years UNICEF has undertaken an annual process to update its global databases, called Country Reporting on Indicators for Goals (CRING). This exercise is done in close collaboration with UNICEF country offices with the purpose of ensuring that UNICEF global databases contain updated and internationally comparable data. UNICEF country offices are invited to submit, through an online system, nationally representative data for over 100 key indicators on the well-being of women and children, including stunting. The country office staff work with local counterparts to ensure the most relevant data are shared. Updates sent by the country offices are then reviewed by sector specialists at UNICEF headquarters to check for consistency and overall data quality of the submitted estimates and re-analysis where possible. This review is based on a set of objective criteria to ensure that only the most reliable information is included in the databases. Once reviewed, feedback is made available on whether or not specific data points are accepted, and if not, the reasons why. UNICEF uses these data obtained through CRING to feed into the joint dataset. The World Bank Group provides estimates available through the Living Standard Measurement Surveys (LSMS) which usually requires re-analysis of datasets given that the LSMS reports often do not tabulate the stunting data.

Data sources are compiled and reviewed throughout the year.

he updated country dataset as well as global and regional estimates are released annually, to coincide with SDG reporting updates by The United Nations Statistical Division (UNSD), generally in March.

Data providers vary and most commonly are ministries of health, national offices of statistics or national institutes of nutrition.

1. Recommendations for data collection, analysis and reporting on anthropometric indicators in children under 5 years old. Geneva: World Health Organization and the United Nations Children’s Fund (UNICEF), 2019. Licence: CC BY-NC-SA 3.0 IGO.

2. United Nations Children’s Fund, World Health Organization, The World Bank (2012). UNICEFWHO-World Bank Joint Child Malnutrition Estimates. (UNICEF, New York; WHO, Geneva; The World Bank, Washington, DC; 2012).

3. de Onis M, Blössner M, Borghi E, et al. (2004), Methodology for estimating regional and global trends of childhood malnutrition. Int J Epidemiol, 33(6):1260-70.

4. Yang H and de Onis M. Algorithms for converting estimates of child malnutrition based on the NCHS reference into estimates based on the WHO Child Growth Standards BMC Pediatrics 2008, 8:19 (05 May 2008) (http://www.biomedcentral.com/1471-2431/8/19).

Country trajectories and assessment towards the stunting, wasting and overweight targets at the national level were determined using the joint malnutrition country dataset (March 2020) and are largely in alignment with the WHO-UNICEF Technical Expert Advisory Group on Nutrition Monitoring rules (‘Methodology for Monitoring Progress towards the Global nutrition Targets for 2025: Technical report’, World Health Organization and United Nations Children’s Fund, June 2017, available at . The interagency assessment on country progress was made towards the 2025 World Health Assembly targets (and not the recently proposed 2030 targets) for this exercise.

While the WHO-UNICEF 2017 rules were used as much as possible, since this report uses the same 5 categories for all SDG indicators (on track, acceleration needed, target met, insufficient trend data, and no data) (Table 1) the current report does not directly align with the latest WHO-UNICEF country assessments published elsewhere.

The ‘on track’ category follows the WHO-UNICEF rules for stunting and overweight (Table 2). For wasting the WHO-UNICEF rules applied to categorize a country as ‘on track’ are instead used to assign an assessment of ‘target met’ in this report since the rules designate a country as ‘on track’ if the prevalence is <5% which is the 2025 target; there is no assessment for ‘on track’ for wasting in this report. The ‘acceleration needed’ category is based on a combination of prevalence and average annual progress rates depending on the indicator. However, the ‘acceleration needed’ category does not exist in the WHO-UNICEF 2017 rules and was made for this report by combining two categories from the WHO-UNICEF 2017 rules of (i) off track: some progress; and (ii) off track: no progress or worsening (Table 1). This report also made an additional classification not within the WHO-UNICEF 2017 rules. This was applied to any country for which the most recent estimate between 2013 and 2019 was < 3 per cent for stunting or overweight prevalence or < 5 per cent for wasting prevalence. This category of ‘target met’ was also applied to countries which have already achieved a 40 per cent reduction in the number of stunted children according to their annual progress rates assessment (Table 2). Apart from countries in the ‘target met’ category, countries that did not have at least two data points since 2008 and at least one data point beyond 2012, were classified as having ‘insufficient trend data’. Countries without any data point after 2000 were classified as ‘no data’. Note that for stunting and overweight, the JME group is developing county level model-based estimates which are anticipated for release in 2021. The assessments presented in this report may therefore change in the near future.