Stunting of Growth in Developing Countries
Introduction
Stunting, defined as length for age more than 2 standard deviations below the median for the World Health Organization (WHO) growth reference standards, is an indicator of chronic malnutrition associated with adverse health and cognitive outcomes during childhood that persist into adulthood. In 2020, 149 million children were stunted [1]. As with previous years, the rate of decline has been disappointingly slow, therefore the global target of reducing the number of children aged under 5 years who are stunted to 100 million by 2025 will not be met [1]. Only 25% of countries were on track to meet the UN Sustainable Development Goal (SDG) target for stunting in 2020, with the largest proportion being in the WHO region of Asia versus less than 10% in Africa [1]. However, for many low- and middle income countries (LMICs) with fragile economies and majority vulnerable populations, any progress that had been made towards addressing the immediate and underlying causes of stunting, such as access to adequate nutrition for women and their infants, quality maternal and child health services, and poverty reduction, has been reversed as resources have been diverted to dealing with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic [2]. Although the full impact of the pandemic has not yet been accounted for in the current global trends for stunting, we expect it to be severe and sustained for years to come [2]. Therefore, significant investment in addressing both the nutrition- sensitive and nutrition-specific causes of stunting will be required in countries hardest hit. Indeed, as many LMICs are unlikely to meet any of the UN SDG targets for health, nutrition, poverty, and climate amongst others, there is now a call to consider revising the SDGs in the context of the social and economic devastation that the pandemic has caused [3]. There is therefore an urgent need to design and implement innovative strategies to address childhood stunting underpinned by a better understanding of the complex mechanisms of early childhood stunting in different contexts, particularly those where there has been limited progress in reducing the rates. In this chapter, we have selected recently published papers on stunting and growth in childhood based on research that seeks to elucidate the mechanisms of early childhood stunting and its impact on long-term growth and cognitive outcomes. We also include recent data on regional patterns of childhood stunting, highlighting how between- and within- country inequities influence the trends that are observed over time. We also consider the often-overlooked nutritional needs of children with cerebral palsy and highlight the need to generate evidence for targeted community-level interventions for them. We include data on recently completed intervention trials of both nutrition-sensitive and nutrition- specific interventions targeted at various timepoints in the lifespan, including preconception, pregnancy, and early infancy. In the perspectives, we consider the role of effectiveness trials in the design and implementation of integrated evidence-based interventions to address childhood stunting.
Factors associated with stunting among children under 5 years in five South Asian countries (2014–2018): analysis of demographic health surveys
Comments: This was a retrospective analysis of demographic health surveillance data from 2014 to 2018 for children under 5 years of age from five South Asian countries, including Bangladesh, India, Nepal, the Maldives, and Pakistan. The aim was to evaluate factors associated with stunting in children across these different countries. A weighted sample of 564,518 children was included in the analysis accounting for differences in population size between countries. The overall pooled prevalence of stunted children under 5 years was 35%; highest in India (38%, and similar rates in Pakistan, Bangladesh, and Nepal) and lowest in the Maldives (15%). Indeed, children born in India, Pakistan, Bangladesh, and Nepal had 2-fold increased odds of being stunted under 5 years. This difference possibly mirrors the disparities in access to health, living standards, and the socioeconomic indices between the Maldives and the other four South Asian countries. Across all countries those with no education, maternal undernutrition (mother’s short stature and BMI ≤18.5), maternal reduced access to health care (attended less than 3 ANC visits, children born at home, 2nd/3rd birth order with less than or equal to a 2-year interval), and belonging to the poorest households were more likely to be stunted. This study adds to the body of evidence that highlights the complex interaction of nutrition-sensitive and specific factors in the etiology of childhood stunting and the need for an integrated approach to interventions that address both the direct and underlying factors.
A multilevel analysis of individual, household and community level factors on stunting among children aged 6–59 months in Eswatini: a secondary analysis of the Eswatini 2010 and 2014 Multiple Indicator Cluster Surveys
Comments: This was a secondary data analysis of Multiple Indicator Cluster Surveys four years apart in Eswatini, in southern Africa, where nearly a quarter of children aged under 2 years are stunted. The aim was to determine the individual, household, and community- level factors associated with childhood stunting in Eswatini over time. Nearly 2,000 children aged 6–59 months were included in the analysis at each of the two timepoints. During this interval stunting decreased significantly from 31.4 to 25.5%. When the researchers evaluated the factors that were associated with stunting overall, children from wealthier households were less likely to be stunted versus children from poorer households at both time points. However, other factors such as sanitation were significantly associated with stunting in 2010 (2-fold odds of being stunted were observed among children from households with a pit latrine/no toilet facility versus households with flushing toilets), but in 2014 this association was not significant. The region of residence also showed a similar pattern with a 2-fold increase in odds of stunting in Shiselweni versus Lubombo, which were both rural in 2010; however, this difference was not evident in 2014. The changes between the two surveys were attributed to multiagency programs including targeted nutrition interventions for undernourished children alongside improving access to safe water in communities and poverty alleviation that were implemented in many rural communities in Eswatini. This further highlights the potential gains that
Machine learning model demonstrates stunting at birth and systemic inflammatory biomarkers as predictors of subsequent infant growth – a four-year prospective study
Comments: This was a sub-analysis from a 4-year prospective study in a rural area in Pakistan that sought to explore child growth patterns through 48 months of age to assess for recovery after growth faltering and evaluate the predictors of growth at birth. They used a machine learning approach (the random forests analysis) to determine the predictors of stunting at 18 months. They managed to collect sufficient additional data on 107/308 (28% of children from the original study). They found high rates of stunting among the children in this cohort – with 51% of infants stunted at birth, 64% at 18 months, and 54% at 48 months. Most children who were stunted at 18 months were stunted at 48 months. The height-for-age Z-score (HAZ) at birth was the most important predictor of HAZ at 18 months. In addition, the biomarkers indicating systemic inflammation, including AGP (alpha-1-acid glycoprotein), CRP (C-reactive protein), and IL1 (interleukin-1), were also strong predictors of subsequent HAZ. Although the sample size is relatively small, this exploratory study highlights the key challenge of reversing stunting after intrauterine growth restriction has occurred with recurrent exposures to pathogens during infancy resulting in systemic inflammation. Continued focus on interventions at conception, antenatally, at birth, and early infancy in children at risk for stunting is warranted.
Adaptation of the small intestine to microbial enteropathogens in Zambian children with stunting
Comments: This was an exploratory study that sought to elucidate the mechanisms by which environmental enteropathy leads to stunting among children in Lusaka, Zambia. At baseline, 297 children with stunting (aged 2–17 months) and 46 unmatched controls (aged 1–5 months) were recruited. The stunted children received daily a cornmealsoy blend, an egg, and a micronutrient sprinkle, and were followed up to 24 months of age. Children who had “non-responsive” stunting after 4–6 months of supplementation were found to have declining circulating lipopolysaccharide and mucosal leakiness with increasing age even in the presence of intestinal damage associated with the persistence of pathogens. They also found that microbial translocation was reduced in the context of environmental enteropathy with villus blunting, this is at the cost of impaired growth. They therefore postulated that environmental enteropathy is an adaptation to enable short-term survival whilst “sacrificing” long-term nutrition. This has implications for the design of future interventions that should enhance epithelia healing and reduce systemic inflammation to achieve catch-up growth.
Nutritional status of children with cerebral palsy in remote Sumba Island of Indonesia: a community-based key informants study
Comments: This survey, conducted in rural Indonesia, found very high rates of severe stunting and associated underweight among 130 children aged less than 18 years identified with cerebral palsy. They found that children with gross motor impairment often had associated speech and swallowing difficulties and therefore invariably require support with feeding to achieve optimal nutrient intake. Epilepsy was also significantly associated with stunting. This paper highlights the plight of an often overlooked but important group of children who require targeted evidence-based interventions at a community level to enhance their growth, cognitive and motor development, and wellbeing. There is an urgent need to co-design and evaluate these interventions with families and communities.
Campylobacter colonization, environmental enteric dysfunction, stunting, and associated risk factors among young children in rural Ethiopia: a cross-sectional study from the Campylobacter Genomics and Environmental Enteric Dysfunction (CAGED) project
Comments: This cross-sectional study conducted in rural Ethiopia sought to describe the prevalence of Campylobacter colonization, environmental enteric dysfunction (EED), and stunting, and evaluate potential risk factors among 102 children aged 12–16 months. They found high rates of EED (50%) and stunting (41%). In this context more than half the children had consumed animal source foods in the preceding 24 h as animal husbandry was common. Although most households had access to an improved source of drinking water, sanitation was poor, with open defecation or unimproved latrines. Interestingly, breastfeeding and consumption of animal source foods increased the odds of Campylobacter detection by PCR, while improved drinking water supply decreased the odds of EED. Probably due to the small sample size no risk factors were significantly associated with stunting. Although not definitive, this study provides some useful preliminary data to inform the design of future studies to elucidate the reservoirs and transmission pathways of Campylobacter spp. and evaluate their role in the etiology of EED and stunting.
Does use of solid fuels for cooking contribute to childhood stunting? A longitudinal data analysis from low- and middle-income countries
Comments: This study used the longitudinal data from the Young Lives Study (YLS) in Ethiopia, India, Peru and Vietnam, conducted in 2002 and 2006–2007 to evaluate the effect of solid fuels for cooking on childhood stunting among children aged 5–76 months. The key finding was that the odds of stunting were much lower among children living in households using solid fuels than among children in households using cleaner fuels for cooking, except in Ethiopia. Further research is required to determine the potential mechanisms of this interaction and the reason for the discrepancy of findings in Ethiopia. Nevertheless, reduction of household exposure to solid fuels and smoke will also improve lung health among the children and other household members.
References
1 World Health Organization. Levels and trends in child malnutrition: UNICEF/WHO/The World Bank Group joint child malnutrition estimates: key findings of the 2021 edition. https://www.who.int/publications/i/ item/9789240025257 (accessed November 28, 2021).
2 Naidoo R, Fisher B. Reset sustainable development goals for a pandemic world. Nature. 2020;583:198–201.
3 Time to revise the sustainable development goals. Nature. 2020;583:331–2.
