Post by: Sophie Budge What?! I'm not small! It's the world that's too big! - Hiromu Arakawa A persistent and pressing issue, malnutrition is a key public health issue facing the globe. Of that fact, epidemiologists, nutritionists, public health specialists, economists, politicians and academics have no doubt. Stunting, a chronic form of malnutrition (or more precisely, undernutrition, although that itself is contentious [1]), is essentially a category of linear growth failure – ‘failure’ in comparison to a global reference standard of optimal child growth [2]. To be ‘stunted’ is to belong in the bracket of a HAZ score (height-for-age) <–2 SD below this global reference. And that’s so agreeable – an efficient, tidy measure which affords some order in a world overwhelmed with linking exposures to outcomes and outcomes to numbers. HAZ <–2 SD can be used to describe point prevalence and time trends of stunted children, both within and across populations, and at local, national and global levels. It’s used to a point which seems an infectious obsession (a key insight by the intrepid Lawrence Haddad). But what really does it mean for a child to be ‘stunted’? And why this obsession? And interventions which focus on stunting as an outcome − what exactly are they (we) trying to solve? Seven eight-year-old children stand in front of a wall with the line depicting the average height according to the WHO Child Growth Standards [3]. First let’s consider how we use the term – as an event that has happened – by the way we write the term: Stunted. Basic grammatical rules state that ‘−ed’ is added to verbs ‘to form their past tense or past participle’ and to nouns ‘to form an adjective to describe someone or something’. Last year’s Joint Child Malnutrition Estimates report estimated that 21.9% of the world’s under-fives were stunted. So 21.9% of children were/are stunted, might become stunted, were/are stunted but might not be later, or all? This might seem pedantic, but it deserves some consideration when we consider the age(s) at which stunting happens. Attempting to define the precise occurrence and development of stunting is difficult due to a lack of time-series data. What we do know is that (at least some) growth failure probably starts in utero (where maternal size and nutritional status contribute) and falters dramatically up to two years of age [4]. This is the period in which interventions and policy typically focus their efforts. However, adolescents can also become stunted [5] and though catch-up growth can occur, accelerated growth may also trigger early puberty, limiting final adult height.6 The timing and tempo of growth between girls and boys varies greatly, as does final adult height [7]. So were these adults born stunted? Did they ‘become’ stunted at some indiscriminate point? Were they stunted as infants, or as adolescents, but were not later on? Possibly [7,8]. Research on the timing of stunting and long-term outcomes have important contributions to make here. But back to grammar. Removing the ‘–ed’ and adding ‘−ing’ spans tenses: stunting as a process, or a gradation. And that’s really the point (I got there). A static category, an arbitrary cut-off point, of <–2 SD misses a substantial portion of children who haven’t grown properly and might never (or might then grow too fast, limiting adult height). Linear growth failure. The cut-off point not only underestimates the burden of those not growing but also dilutes associations of cause and effect. Furthermore, when describing the pathophysiology of stunting, there can surely be no biological or clinical changes immediately below or above this cut off [9]. I’ve measured infants who translated to a −1.9 z-score – what about them? I don’t dispute the evidence that links stunted growth to lower labour market productivity and economic loss [10], nor with reduced cognitive and motor outcomes [11], or poorer socioemotional development [12]. But there are issues with what meaning we impart when categorising children as stunted, aside from the great chunk of children immediately above (and just below) the line. The implications of the term have narrowed and contracted from a population marker of environmental adequacy to the level that an individual stunted infant is diseased [1,4], or more appropriately, suffering a syndrome [4]. What that individual infant is actually suffering is a myriad of environmental insults: a complicated interaction of factors which encompass (but is not limited to) a lack of basic hygiene, safe water and sanitation, chronically poor dietary quality and quantity, low caregiver education, infectious disease, unfavourable contextual gender roles, low employment and financial insecurity, poor healthcare infrastructure and political instability. UNICEF admit: ' …stunting is about far more than the height of an individual child – every community has shorter and taller children. Rather, it is a stark sign that children in a community are not developing well, physically and mentally [13].' So we could say that to be stunted (or stunting) is perhaps less a manifestation of malnutrition (or again, more specifically undernutrition), than of chronic poverty. And poverty is inherited, too [14]. In high-income nations when we started growing better, it was when far-reaching and comprehensive health and social services were in place [15–17]. In high-income countries, public health interventions that overlapped with improved child health outcomes were the result of decades of large-scale public investment [18]. Considering examples of countries where stunting has dramatically declined, like Brazil, it follows similar long periods of serious investment and sustained, coordinated action from (and integration of) related sectors, e.g. nutrition, health and social care and water, sanitation and hygiene [19]. In all of these contexts, environmental change happened slowly, incrementally – with changes in outcomes occurring even slower [17,18]. The upper estimate of impact for high quality trials seeking to reduce stunting may therefore be unrealistic – especially with household-level interventions that focus on only one or few of the more direct causes [20]. A woman sweeps outside her home in Sidama zone, SNNP region, Ethiopia. Variation in height will always remain (don’t I know it at a staggering 5’1”). That is not to say that linear growth failure does not exist: simply that population height is a continuous gradation of nutritional (environmental) status. This is important to keep in perspective as there are developmental consequences for all children at different points of this gradation [21]. Also of high importance is the rate at which infants grow [22], which may be more useful when interpreting the impact of interventions. To be stunted is to have stunted and to be stunting: it is a process, a reflection of environmental conditions before, during and for a period after birth. It is as dynamic and changeable as the world in which infants live. Perhaps, then, what we really need to aim for is a shift of the child population growth curve to the right. This will necessitate creating and maintaining hugely favourable public health conditions [23] and a high threshold of socioeconomic and living standards [24] – alongside a great deal of time. Again, let’s stop to ask ourselves – what is it we really want to achieve? To quote from another, why should we ‘solve a so-called ‘stunting problem’’ whilst allowing the problem of poverty to remain? (p.280 in [25]). Infection causes malnutrition. Poor dietary quality and quantity causes malnutrition. But so does ineffective governance, economic disadvantage and many other distal factors. We have to ask ourselves: if we prevented these upstream factors, would we ever reach the outcome? We have to ask ourselves again: what is it we are trying to achieve? I am driven to debate this story we are telling about stunting, because this story matters. How we both define and discuss the causes of linear growth failure determines what we do with science, investments and policy. When a story is widely known, people accept it, repeat it, get used to it, and then work out how it might best serve themselves. We know on some level it’s perhaps not an accurate story, or the best way to tell it, but we know the narrative and we work with it – this is what I do. Accepting the wider, broader and much more tangled version is hard. It’s scary. How do we go about discussing the need for mammoth, systematic change? But I charge you to consider it. I call on our collective wisdom to accept that perhaps our aims can be flawed – that perhaps we are collecting around the telling and re-telling of a slight un-truth. I call for a collective vision to decide to discuss the causes of malnutrition in a way that really lets us transform it as an outcome. Let’s not let ourselves be distracted. There’s a wood beyond the trees. Two young children play with an old tyre in rural Gambia. Thanks go to Prof Paula Griffiths at Loughborough University for her insight and comments on this piece. Sophie Budge is a PhD student at Cranfield University with People in Need and runs the WASHing Up site. She is interested in global child health, epidemiology and nutrition. You can follow her on twitter here. 1. Perumal N, Bassani DG, Roth DE. Use and misuse of stunting as a measure of child health. J Nutr. 2018; 148(3): 311-315.
2. WHO Multicentre Growth Reference Study Group. WHO Child Growth Standards. Length/Height-for-Age, Weight-for-Age, Weight-for-Length, Weight-for-Height and Body Mass Index-for-Age: Methods and Development. Department of Nutrition Health and Development. Geneva: World Health Organization; 2006. 3. Seven eight-year-old children stand in front of a wall with the line depicting the average height according to the WHO Child Growth Standards. Available online at: https://stefvanbuuren.name/dbook1/sec-stunting.html. 4. Prendergast A, Humphrey J. The stunting syndrome in developing countries. Paediatr Int Child Heal. 2014; 34(4): 250–265. 5. Akresh R, Bhalotra S, Leone M, Osili UO. War and Stature: Growing up during the Nigerian Civil War. 2011. 6. Proos LA. Anthropometry in adolescence-secular trends, adoption, ethnic and environmental differences. Horm Res. 1993; 39(S3): 18-24. 7. Bosch AM, Baqui AH, van Ginneken JK. Early-life determinants of stunted adolescent girls and boys in Matlab, Bangladesh. J Heal Popul Nutr. 2008; 26(2): 189-199. 8. Prentice AM, Ward KA, Goldberg GR, et al. Critical windows for nutritional interventions against stunting. Am J Clin Nutr. 2013; 97(5): 911-918. 9. Leroy JL, Frongillo EA. Perspective: What Does Stunting Really Mean? A Critical Review of the Evidence. Adv Nutr. 2019; 10(2): 196–204. 10. Hoddinott J, Alderman H, Behrman J, Haddad L, Horton S. The economic rationale for investing in stunting reduction. Mater Child Nutr. 2013;9(S2): 69–82. 11. Sudfeld CR, McCoy DC, Danaei G, et al. Linear growth and child development in low- and middle-income countries: A meta-analysis. Pediatrics. 2015; 135(5): e1266-e1275. 12. Pollitt E. A developmental view of the undernourished child: Background and purpose of the study in Pangalengan, Indonesia. Eur J Clin Nutr. 2000; 54(2): S2-S10. 13. UNICEF. The State of the World’s Children 2019. Children, Food and Nutrition: Growing Well in a Changing World. New York; 2019. 14. Martorell R, Zongrone A. Intergenerational influences on child growth and undernutrition. Paediatr Perinat Epidimiol. 2012; 26(S1): 302–314. 15. Alsan M, Goldin C. Watersheds in Infant Mortality: The Role of Effective Water and Sewerage Infrastructure, 1880 to 1915. 2015. Natl Bur Econ Res, Work Pap Ser No. 21263. 16. Cutler D, Deaton A, Lleras-Muney A. The determinants of mortality. J Econ Perspect. 2006; 20(3): 97–120. 17. Bell F, Millward R. Public health expenditures and mortality in England and Wales, 1870-1914. Contin Chang. 1998; 13(2): 221–249. 18. Cumming O, Arnold BF, Ban R, et al. The implications of three major new trials for the effect of water, sanitation and hygiene on childhood diarrhea and stunting: a consensus statement. BMC Med. 2019; 17(173). 19. Monteiro CA, Benicio MHD, Konno SC, Silva ACF da, Lima ALL de, Conde WL. Causes for the decline in child under-nutrition in Brazil, 1996-2007. Rev Saude Publica, 2009; 43(1): 35–43. 20. Global Alliance for Improved Nutrition (GAIN). Are we misusing stunting as a measure of child nutrition? Available online at: https://www.gainhealth.org/media/news/are-we-misusing-stunting-measure-child-nutrition. 21. Spears D. Height and cognitive achievement among Indian children. Econ Hum Biol. 2012; 10: 210-219. 22. Costello AM. Growth velocity and stunting in rural Nepal. Arch Dis Child. 1989; 64(10): 1478-1482. 23. Hatton TJ. How have Europeans grown so tall? Oxf Econ Pap. 2014; 66(2): 349–372. 24. Husseini M, Darboe MK, Moore SE, Nabwera HM, Prentice AM. Thresholds of socio-economic and environmental conditions necessary to escape from childhood malnutrition: A natural experiment in rural Gambia. BMC Med. 2018; 16(1): 199.. 25. Waterlow JC, Nestle Nutrition SA. Linear Growth Retardation in Less Developed Countries. Nestlé Nu. New York: Raven Press; 1988.
2 Comments
Barry Bogin
12/5/2020 09:14:04
Sophie -- your are asking all the right questions. Brilliant essay!
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Sophie Budge
6/6/2020 01:20:13
Thanks so much Barry!
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