Stunted growth

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For stunting of growth in plants, see Plant nutrition.

Stunted growth or stunting is a reduced growth rate in human development. It is a primary manifestation of malnutrition and recurrent infections, such as diarrhea and helminthiasis, in early childhood and even before birth, due to malnutrition during fetal development brought on by a malnourished mother. The definition of stunting according to the World Health Organisation (WHO) is for the "height for age" value to be less than two standard deviations of the WHO Child Growth Standards median.[1]

As of 2012 an estimated 162 million children under 5 years of age, or 25%, were stunted in 2012. More than 90% of the world's stunted children live in Africa and Asia, where respectively 36% and 56% of children are affected.[2] Once established, stunting and its effects typically become permanent. Stunted children may never regain the height lost as a result of stunting, and most children will never gain the corresponding body weight. Living in an environment where many people defecate in the open due to lack of sanitation, is an important cause of stunted growth in children, for example in India.[3]

Impacts[edit]

Stunted growth in children has the following public health impacts apart from the obvious impact of shorter stature of the person affected:

  • greater risk for illness and premature death[1]
  • may result in delayed mental development and therefore poorer school performance and later on reduced productivity in the work force[1]
  • reduced cognitive capacity
  • Women of shorter stature have a greater risk for complications during child birth due to their smaller pelvis, and are at risk of delivering a baby with low birth weight[1]
  • Stunted growth can even be passed on to the next generation (this is called the "intergenerational cycle of malnutrition")[1]

Causes[edit]

Children living in unsanitary conditions in an urban slum in India, at risk of diarrhea and stunted growth
Child next to open sewer in slum in Kampala, Uganda, at risk of diarrhea and stunted growth

Whilst the principal cause for stunted growth in children used to be regarded as simply malnutrition, there is increasing agreement that lack of sanitation (open defecation) and associated diseases, such as recurrent diarrhoea, intestinal worm infections (helminthiasis) and a condition called environmental enteropathy all are important causes, too.[4] Environmental enteropathy is a syndrome causing changes in the small intestine of persons and can be brought on due to lacking basic sanitary facilities and being exposed to faecal contamination on a long-term basis.[4]

Research on a global level has found that the proportion of stunting that could be attributed to five or more episodes of diarrhoea before two years of age was 25%.[5] Since diarrhoea is closely linked with water, sanitation and hygience (WASH), this is a good indicator for the connection between WASH and stunted growth. The understanding of the complex interdependence between nutrition, stunted growth and WASH has increased in recent years.

Diagnosis[edit]

Growth stunting is identified by comparing measurements of children's heights to the World Health Organization 2006 growth reference population: children who fall below the fifth percentile of the reference population in height for age are defined as stunted, regardless of the reason. The lower than fifth percentile corresponds to less than two standard deviations of the WHO Child Growth Standards median.

As an indicator of nutritional status, comparisons of children's measurements with growth reference curves may be used differently for populations of children than for individual children. The fact that an individual child falls below the fifth percentile for height for age on a growth reference curve may reflect normal variation in growth within a population: the individual child may be short simply because both parents carried genes for shortness and not because of inadequate nutrition. However, if substantially more than 5% of an identified child population have height for age that is less than the fifth percentile on the reference curve, then the population is said to have a higher-than-expected prevalence of stunting, and malnutrition is generally the first cause considered.

Prevention[edit]

Three main things are needed to reduce stunting:[6]

  • a kind of environment where political commitment can thrive (also called an "enabling environment")
  • applying several nutritional modifications or changes in a population on a large scale which have a high benefit and a low cost
  • a strong foundation that can drive change (food security, empowerment of women and a supportive health environment through increasing access to safe water and sanitation).

To prevent stunting, it is not just a matter of providing better nutrition but also access to clean water, improved sanitation (hygenic toilets) and hand washing at critical times (summarised as "WASH"). Without provision of toilets, prevention of tropical intestinal diseases, which may affect almost all children in the developing world and lead to stunting will not be possible.[7]

Studies have looked at ranking the underlying determinants in terms of their potency in reducing child stunting and found in the order of potency:[8]

  • percent of dietary energy from non-staples (greatest impact)
  • access to sanitation and women’s education
  • access to safe water
  • women’s empowerment as measured by the female-to-male life expectancy ratio
  • per capita dietary energy supply

Three of these determinants should receive attention in particular: access to sanitation, diversity of calorie sources from food supplies, and women’s empowerment. A study by the Institute of Development Studies has stressed that: "The first two should be prioritized because they have strong impacts yet are farthest below their desired levels".[8]

The goal of UN agencies, governments and NGO is now to optimise nutrition during the first 1000 days of a child’s life, from pregnancy to the child’s second birthday, in order to reduce the prevalence of stunting.[9] The first 1000 days in a child's life are a crucial "window of opportunity" because the brain develops rapidly, laying the foundation for future cognitive and social ability. Furthermore, it is also the time when young children are the most at risk of infections that lead to diarrhoea. It is the time when they stop breast feading (weaning process), begin to crawl, put things in their mouths and become exposed to faecal matter from open defecation and environmental enteropathies.[9]

Epidemiology[edit]

World map showing % of children under height for age (i.e. with stunted growth)

According to the World Health organisation if less than 20% of the population is affected by stunting, this is regarded as  "low prevalence" in terms of public health significance.[1] Values of 40% or more are regarded as very high prevalence, and values in between as medium to high prevalence.[1]

UNICEF has estimated that: "Globally, more than one quarter (26 per cent) of children under 5 years of age were stunted in 2011 – roughly 165 million children worldwide."[10] and "In sub-Saharan Africa, 40 per cent of children under 5 years of age are stunted; in South Asia, 39 per cent are stunted."[10] The four countries with the highest prevalence are Timor-Leste, Burundi, Niger and Madagascar where more than half of children under 5 years old are stunted.[10]

Research[edit]

The Water and Sanitation Program of the World Bank has investigated links between lack of sanitation and stunting in Vietnam and Lao PDR.[11] For example in Vietnam it was found that lack of sanitation in rural villages in mountainous regions of Vietnam led to five-year-old children being 3.7 cm shorter than healthy children living in villages with good access to sanitation.[12] This difference in height is irreversible and matters a great deal for a child’s cognitive development and future productive potential.

One study conducted in a rural area in Zimbabwe illustrates the impact malnutrition has on growth. The area is known for poor farming conditions and prevalent malnourishment. Children ages 6–17 in the area were assessed for height, weight, and body mass index (BMI). The data recorded was compared with both American and other African countries average heights. Compared with the American averages, the Zimbabwean boys' height and weight dropped as low as the 10th percentile in some age groups and showed no sign of catch-up growth during the mid-teens. Zimbabwean girls' height and weight were not as low, but did drop as low as the 25th percentile. However, catch-up growth did occur during mid-teens and by 16 and 17, the girls average was close to the 50th percentile. Olivier, Semproli, Pettener, and Toselli, sums it up by saying that "the adverse socioeconomic environment and the low levels of food availability compromise and probably delay the physical development of the affected children in all phases of growth." Also, these data support the theory that lower than average size at early ages could be due to an adaptive mechanism reacting to low food intake.[13]

See also[edit]

References[edit]

  1. ^ a b c d e f g "Nutrition Landscape Information System (NLiS)". WHO. Retrieved 12 November 2014. 
  2. ^ United Nations Children's Fund, World Health Organization, The World Bank. UNICEFWHO- World Bank Joint Child Malnutrition Estimates. (http://data.unicef.org/resources/2013/webapps/nutrition)
  3. ^ Spears, D. (2013). How much international variation in child height can sanitation explain? - Policy research working paper. The World Bank, Sustainable Development Network, Water and Sanitation Program
  4. ^ a b Velleman, Y., Pugh, I. (2013). Under-nutrition and water, sanitation and hygiene - Water, sanitation and hygiene (WASH) play a fundamental role in improving nutritional outcomes. A successful global effort to tackle under-nutrition must include WASH. Briefing Note by WaterAid and Share, UK
  5. ^ Walker, Christa L Fischer; Rudan, Igor; Liu, Li; Nair, Harish; Theodoratou, Evropi; Bhutta, Zulfiqar A; O'Brien, Katherine L; Campbell, Harry; Black, Robert E (April 2013). "Global burden of childhood pneumonia and diarrhoea". The Lancet 381 (9875): 1405–1416. doi:10.1016/S0140-6736(13)60222-6. 
  6. ^ "The Lancet series on Maternal and Child Nutrition". The Lancet. 6 June 2013. Retrieved 8 November 2014. 
  7. ^ Humphrey, JH (19 September 2009). "Child undernutrition, tropical enteropathy, toilets, and handwashing.". Lancet 374 (9694): 1032–5. PMID 19766883. 
  8. ^ a b Smith, L. and Haddad, L. (2014) Reducing Child Undernutrition: Past Drivers and Priorities for the Post-MDG Era, IDS Working Paper 441, IDS (Institute for Development Studies), UK
  9. ^ a b Franck Flachenberg, Regine Kopplow (2014) How to better link WASH and nutrition programmes, Concern Worldwide Technical Briefing Note
  10. ^ a b c UNICEF (2013). Improving child nutrition : the achievable imperative for global progress. United Nations Children’s Fund (UNICEF), New York, USA. ISBN 978-92-806-4686-3. 
  11. ^ Maria Quattri, Susanna Smets, and Viengsompasong Inthavong (2014) Investing in the Next Generation - Children grow taller, and smarter, in rural, mountainous villages of Lao PDR where all community members use improved sanitation, WSP (Water and Sanitation Program), World Bank, USA
  12. ^ Maria Quattri, Susanna Smets, and Minh Thi Hien Nguyen (2014) Investing in the Next Generation - Children grow taller, and smarter, in rural, mountainous villages of Vietnam where community members use improved sanitation, WSP (Water and Sanitation Program), World Bank, USA
  13. ^ Olivieri, F., Semproli, S.,Pettener, D., & Toselli, S. (2007). Growth and malnutrition of rural Zimbabwean children (6-17 years of age). American Journal of Physical Anthropology, 136(2), 214-222. doi:10.1002/ajpa.20797