Stunting of Growth in Developing Countries
Introduction
In 2019, 144 million children were stunted, i.e. length for age more than 2 standard deviations below the median for the World Health Organisation (WHO) growth reference standards. The rate of decline required to meet the target of reducing the number of under 5’s who are stunted globally to 100 million by 2025 has not been achieved [1]. Progress has been particularly slow in sub-Saharan Africa that remains one of the regions with the highest burden of the problem. In 2020, this will be compounded by the impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic that has diminished livelihoods in many already vulnerable communities and significantly reduced access to, and coverage of, maternal and child health services particularly in low- and middle-income countries (LMICs), therefore increasing both poverty and food insecurity [2]. Stunting is an indicator of chronic malnutrition that is associated with adverse health and cognitive outcomes during childhood that persist into adulthood. Greater efforts are therefore required to understand the complex mechanisms of early childhood stunting, factors that influence its persistence in certain populations despite apparent reductions in poverty within regions and countries, to inform the design and implementation of future interventions. 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 adolescent growth and pubertal development. 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. In addition, we include studies that explore the impact of economic growth on childhood stunting particularly across sub-Saharan African countries. We include data on recently completed intervention trials of both nutrition-sensitive and nutrition-specific interventions targeted at various time points in the lifespan including preconception, pregnancy, and early infancy. One of the trials goes beyond reporting of the efficacy results alone and provides data on stakeholder (including both policy makers and the caregivers) perceptions of cost-effectiveness of the intervention, therefore providing key data to inform implementation. Finally, in the perspectives we have included the insights on water sanitation and hygiene (WASH) interventions from three trials conducted in countries with high rates of childhood stunting – WASH-Benefits Bangladesh, WASH-Benefits Kenya and the Sanitation Hygiene Infant Nutrition Efficacy (SHINE) in Zimbabwe. There was no evidence from these trials that low-cost water sanitation and hygiene (WASH) interventions alone or combined with nutrition (maternal and child) interventions sufficiently improved linear growth in early childhood in LMICs. The concept of “Transformative WASH” provides opportunities for multisectoral research and implementation of programmes that could potentially lead to improvements in child health, growth and developmental outcomes. Overall, the studies that we have chosen emphasise the need for better alignment of nutrition and health system interventions to ensure that the most vulnerable mothers and children (due to poverty, adverse climate change, humanitarian crises, or disabilities/cognitive impairment) have equitable access to multilevel interventions that work synergistically to address childhood stunting.
Trends and Pathways
Mapping child growth failure across low- and middle-income countries
Comments: This collaborative project used national survey data including Demographic Health Surveys and Multiple Indicator Surveys from 2000–2017 across 105 LMICs to map out the prevalence and trends in undernutrition amongst children under 5 years. Its findings mirror those from the UNICEF/WHO/World Bank Group Joint Child Malnutrition annual estimates but goes further by providing more granular details about the within- country differences in both the prevalence and trends. For example, although the prevalence of stunting has nearly halved between 2000 and 2017 (i.e., 30% or less) in some coastal western and central sub-Saharan African countries, some states in Nigeria and provinces in Burundi had estimated under 5 stunting prevalence of up to 61% in 2017. This study therefore highlights the impact of inequities, particularly wealth, that impede progress in meeting the global nutrition target of reducing stunting by 40% from 2012 to 2025. It helps to identity regions and communities where more intense targeted interventions are required and will be key to supporting policymakers and other partners including researchers and implementation experts with decisions on resource allocation, research and implementation priorities.
Early childhood linear growth failure in low- and middle-income countries
Comments: Complementary to the Local Burden of Disease Child Growth Failure Collaborative study above, this study is a pooled analysis of longitudinal studies from 31 cohorts with over 62,000 children aged 0–24 months in LMICs. The aim was to identify the timing of onset or persistence of growth failure to inform the delivery of preventative interventions. This study found that incidence of stunting was highest from birth to 3 months accounting for 40% of children who were stunted between 0 and 24 months. Twelve percent of infants were stunted at birth, and 17% became stunted between birth and 3 months. In addition, reversal of stunting between 0 and 15 months was rare, and relapse was common. These findings confirm that maternal health and nutrition as well as sub-optimal infant feeding and care practice play a significant role in early childhood stunting, hence the need for enhanced integration of nutrition-specific and sensitive intervention with maternal & child health programmes. Partner papers [3, 4] provide a similar analysis for wasting and examine the predictors of early childhood malnutrition. Maternal body size remains an important determinant.
Drivers of under-five stunting trend in 14 low- and middle-income countries since the turn of the millennium: A multilevel pooled analysis of 50 demographic and health surveys
Comments: This was a pooled analysis of demographic health surveys since 2000 from 14 LMICs predominantly in sub-Saharan Africa and South Asia that had data for at least three time points. The aim was to evaluate the factors associated with childhood stunting trends in these countries. More than 300,000 children under 5 years were included in their analysis. Overall, in all countries they found that the prevalence of stunting was declining at an annual rate of 1.04 percent points. Urbanisation, increase in women’s decision-making power, households’ access to improved sanitation facilities and drinking water sources, and children’s access to all basic vaccinations, a decrease in the prevalence of low birth weight and initiation of breastfeeding ≤24 h after birth were associated with a lower probability of stunting. These factors encompass both nutrition-sensitive and nutrition-specific interventions that can help guide the development of more targeted delivery strategies particularly for the most vulnerable communities.
Does economic growth reduce childhood stunting? A multicountry analysis of 89 demographic and health surveys in sub-Saharan Africa
Comments: This analysis addresses the important question that many policymakers, researchers and implementers have been asking about the impact of economic growth on child nutrition transition in sub-Saharan Africa. In Brazil, economic development led to significant decreases in undernutrition in both children and adults, with worryingly more obesity noted in adults even in low-income families [5]. In this study, Yaya et al. used data from nationally representative demographic health surveys conducted between 1987 and 2016 in 20 countries in sub-Saharan Africa. They also used national aggregate data for gross domestic product (GDP) per capita according to the World Bank’s World Development Indicators. They had anthropometric data from nearly half a million children. As in other regions of the world experiencing economic development, they found that the odds of stunting decreased by 12% (OR = 0.88, 95% confidence interval [CI]: 0.87–0.90) for every USD 1,000 increase in GDP per capita. However, when they stratified this analysis according to wealth quintiles, they found that the odds of stunting decreased by 15% (OR 0.85, 95% CI: 0.80– 0.90) for every USD 1,000 increase in GDP per capita among children in the richest wealth quintile, but there was no association among children in the poorest quintile. These findings again highlight the need for policies that address societal wealth inequities in communities in LMICs, without which a significant reduction in stunting in the high burden countries will not be achieved.
Mapping the effects of drought on child stunting
Comments: Food insecurity is a key driver of stunting and is closely linked to climate change globally. In this study, Copper et al. sought to map where child nutrition is vulnerable to rainfall shocks and explore the factors that moderate vulnerability. In this analysis, they used demographic health surveillance and climate data from 53 LMICs as well as data on sensitivity of local food systems and their adaptive capacity to drought. Their key finding was that child height-for-age Z-scores decrease with rainfall deficits. Using modelling, they found that most drought-vulnerable children are in arid areas with weak governments and little international trade that are incidentally conflict zones such as South Sudan and Yemen. These findings provide key insights into the vulnerability of children in these arid and conflict regions to climate change and therefore the urgency of developing resilient food systems to prevent undernutrition, particularly stunting in these populations.
Prevalence of underweight, wasting and stunting among young children with a significant cognitive delay in 47 low-income and middle-income countries
Comments: Children with cognitive delay in LMICs are vulnerable and often excluded from mainstream education and other programmes to support their development and wellbeing [6]. In this secondary data analysis, Emmerson et al. used data from UNICEF’s Multiple Indicator Cluster Surveys for 47 LMICs of more than 160,000 children aged 4–5 years. In this dataset, 12.3% (95% CI: 11.8–12.8%) were classified as having significant cognitive delay, and these children were more than twice as likely to be undernourished including severely stunted. This association was most marked in children from poor households. The study highlights how vulnerable children with disabilities are to undernutrition (including stunting) and its adverse health and social outcomes and the need for an integrated approach incorporating health, nutrition and early child development strategies to optimise their outcomes.
Stunting is preceded by intestinal mucosal damage and microbiome changes and is associated with systemic inflammation in a cohort of Peruvian infants
Comments: Stunting in associated with environmental enteric dysfunction is common among children living in unhygienic environments in LMICs [7]. In this study, Zambruni et al. sought to investigate the relationship between linear growth, intestinal damage and systemic infection in infants at risk of stunting in two rural communities in Peru. They recruited and followed up 78 infants between 5 and 12 months over 6 months spanning across the dry and rainy seasons. They excluded infants who were born preterm, had severe chronic illness, or previously been diagnosed with failure to thrive. At baseline, they all had a had a length-for-age Z-score (LAZ) >–2. Sixty-one (79%) of children experienced a decline in LAZ scored during the study and 21% (16/75) became stunted. Biomarkers of intestinal damage and markers of systemic inflammation were strongly and inversely correlated with change in LAZ scores over the following months. The microbiota were also altered. These preliminary data provide additional insights into the aetiology of stunting and will inform the design of future interventions.
Does use of solid fuels for cooking contribute to childhood stunting? A longitudinal data analysis from low- and middle-income countries
Comments: Air pollution is common in LMICs and is being explored as a potentially important cause of childhood stunting [8]. In this secondary analysis of longitudinal data (Young Lives Study) from 4 LMICs (Ethiopia, India, Peru and Vietnam) among children 5–76 months, Upadhyay et al. examined the effect of the use of solid cooking fuels among other sociodemographic variables on childhood stunting. Each country had data from two time points 3 or 4 years apart. They found that children from households using solid fuel for cooking were less likely to achieve higher HAZ scores in all countries except Ethiopia. It is not possible to make any definitive conclusions from this study, but the findings can support the development of future longitudinal studies with more robust exposure levels of infants/children to the air pollutants of solid fuel and the incidence of stunting.
Consequences
Stunting trajectories from post-infancy to adolescence in Ethiopia, India, Peru, and Vietnam
Comments: This secondary data analysis uses the Young Lives Study longitudinal data from Ethiopia, India, Peru and Vietnam with more than 7,000 children aged 1–15 years. Across all four countries, 12.9% of children were first stunted under 5 years of age, and 29.6% were first stunted by 12 months of age. More children who were stunted by 12 months remained stunted at 15 years (40.7%) compared to those who were stunted between 1 and 5 years of age (32.3%). About a third of stunted children recover but relapse later in childhood, whilst 13.1% became stunted between the ages of 8–15 years. These data add to the discourse around not limiting interventions to prevent stunting to the first 1,000 days as there is potential for recovery and new onset stunting outside of this “critical window.”
Not water, sanitation and hygiene practice, but timing of stunting is associated with recovery from stunting at 24 months: Results from a multi-country birth cohort study
Comments: This secondary data analysis used data from eight LMICs in the MAL-ED (Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health) birth cohort study with over 2,000 children. Their aim was to investigate the role of WASH on recovery from childhood stunting and its timing. As the title suggests, they found no evidence that WASH influenced recovery from childhood stunting. However, they found that children who were stunted at 18 months were more likely to recover at 24 months compared to those who were stunted at 6 months. This adds to the body of evidence on how the recovery from stunting is influenced by the timing of its onset. Therefore, enhancing efforts to address the causes of stunting at the period of greatest risk of adverse outcomes (first 12 months) is urgently needed.
Interventions
Preconception nutrition intervention improved birth length and reduced stunting and wasting in newborns in South Asia: The Women First Randomized Controlled Trial
Comments: In this secondary analysis, Dhaded et al. used anthropometric data from over 900 neonates (<28 days old) in the South Asian cohort of the Women First Preconceptual trial. Their aim was to evaluate the impact of maternal preconceptual and 1st trimester nutrition interventions on fetal growth in the region. A daily lipid-based micronutrient supplement commencing ≥3 months prior to conception increased birth length by +5.3 mm and LAZ by +0.29 (0.11–0.46, p = 0.0011). There was a 44% (RR =0.56, 95% CI: 0.38–0.82, p = 0.0032) reduction in stunting at birth among the neonates in the preconceptual nutrition arm compared to those in the control arm. In addition, there was a 26% (RR = 0.74 95% CI: 0.66–0.83, p < 0.0001) reduction in small for gestation age and borderline effect in low birth weight (RR = 0.81 95% CI: 0.66–1.00, p = 0.0461). This study provides promising evidence of an intervention that if implemented at scale, could accelerate progress in preventing childhood stunting. It would be useful to see if these findings are replicated in other high burden regions such as sub-Saharan Africa and South America.
Interventions to improve linear growth during exclusive breastfeeding life-stage for children aged 0–6 months living in low- and middle-income countries: A systematic review with network and pairwise meta-analyses
Comments: In this systematic review and meta-analysis, Park et al. sought to evaluate the comparative effectiveness of micronutrients, food supplements, deworming, maternal education, WASH, and kangaroo care, on the first 6 months on infants’ linear growth. Twenty-nine RCTs with over 35,000 mother-infant pairs were included in the metaanalysis. The key findings were that none of the interventions reduced stunting in early infancy. Interestingly, Kangaroo care resulted in small but significant improvements in head circumference (mean difference: 0.20 cm/week; 95% CI: 0.09, 0.31 cm/ week) and length (mean difference: 0.23 cm/week; 95% CI: 0.10, 0.35 cm/week) compared to standard-of-care. As this intervention was limited to 1–6 weeks in trials (indeed also in practice), it was analysed separately. The insufficient data available on the effects of interventions on the linear growth of infants from birth to 6 months rendered their findings inconclusive.
Cost-effectiveness of 4 specialized nutritious foods in the prevention of stunting and wasting in children aged 6–23 months in Burkina Faso: A geographically randomized trial
Comments: This paper focuses of the cost effectiveness of specialised nutritious foods (Corn-Soy Blend Plus, Corn-Soy-Whey Blend with oil, SuperCereal Plus and ready-to-use supplementary food, RUSF) in preventing stunting and wasting among children aged 0–23 months in Burkina Faso. This was a cluster randomised trial with over 6,000 children. Overall, 23% of children were stunted at 23 months, and children who were given Corn-Soy-Whey Blend with oil were twice as likely to be stunted at 23 months than those given Corn-Soy Blend Plus arm (OR: 2.07; 95% CI: 1.46–2.94). The most expensive intervention was RUSF (USD 245 per child enrolled), while Corn-Soy Blend Plus was the cheapest (USD 122) and therefore the most cost-effective. However, none of these specialised nutritious foods prevented growth faltering. Although their findings are key for policymakers tasked with resource allocation, it does not provide information of the reasons for lack of effectiveness of these interventions in preventing growth faltering and for most of them stunting as well. In an embedded study, they explored the factors that influenced the lack of effectiveness of the interventions using quantitative and qualitative methods. Their key findings were that sharing was common, palatability was an issue, and there was lack of adherence to food preparation guidance, and concerns were raised about access to appropriate WASH [9]. Ideally, adherence could have been monitored more closely, but this would have been resource intensive and not provided the key information required for implementing it.
Perspectives and Policy
The implications of three major new trials for the effect of water, sanitation and hygiene on childhood diarrhea and stunting: A consensus statement
Comments: In this paper, the investigators of the three large cluster randomised trials that evaluated the impact of low-cost WASH interventions on childhood undernutrition (including linear growth and stunting rates) provide insights on the interpretation of their findings and next steps. These trials were conducted in countries with high rates of childhood stunting – WASH-Benefits Bangladesh, WASH-Benefits Kenya and the Sanitation Hygiene Infant Nutrition Efficacy (SHINE) in Zimbabwe. The trials conclusively showed that low-cost WASH interventions alone or combined with nutrition (maternal and child) interventions had no effect on childhood linear growth in LMICs. The investigators support a call for a more comprehensive package of interventions, i.e. Transformative WASH, as the next steps to limiting the microbial enteric exposures among infants in unhygienic and impoverished communities in LMICs. Indeed, it is anticipated that the thresholds of WASH required to address childhood stunting will require more investments and a multisectoral approach that comprehensively addresses living standards and poverty [10, 11].
