Stunting of Growth in Developing Countries

Introduction

Stunting, namely length-for-age more than 2 standard deviations below the median for the World Health Organization growth reference standards, is the most common form of childhood malnutrition. It is an indicator of chronic malnutrition that predicts an increased risk of death in childhood as well as being associated with adverse health and cognitive outcomes during childhood that persist into adulthood. In 2020, over 149 million children under 5 years were stunted ^[1]. Many low- and middle-income countries (LMICs) have committed to the sustainable development goal target of eliminating childhood malnutrition by 2030 ^[2], yet with the current global trends, it is unlikely that this will be achieved. Innovative and accelerated efforts are therefore required to enable many LMICs to meet the 2030 global nutrition targets. The ongoing impact of the COVID-19 pandemic, coupled with worsening food security, economic crises, climate change, and conflict, has undoubtedly reversed any gains that had been made prepandemic ^[3]. While about one quarter of all COVID-related childhood deaths are attributed to wasting ^[4] (severe acute malnutrition [SAM]), the impact of childhood stunting is yet to be fully understood ^[5]. In addition, although the impact of socioeconomic inequalities on health outcomes is well-described ^[6], the complexities of how these inequalities influence childhood stunting are less well understood. Indeed, in some communities where short stature is common, there is controversy around whether childhood stunting should be considered a public health problem ^[7].

In this chapter, we have selected recently published papers from June 2021 to June 2022 on stunting and growth in childhood based on research on the antecedents, mechanisms, and complex pathways underpinning childhood stunting. We also include recent data on nutrition-specific and nutrition-sensitive interventions including maternal health/well-being and women’s economic empowerment. Finally, we have included publications that provide insights on how to improve governance, monitoring, and evaluation of nutrition interventions at the grassroots level and provide more robust and timely impact assessments.

Trends and Pathways

Epithelial abnormalities in the small intestine of Zambian children with stunting

Comments: Nutrition supplementation during pregnancy and childhood does not overcome childhood stunting in LMICs, possibly due to environmental enteropathy (EE). EE is a condition of the small intestine that involves loss of villus, reduced absorption, and intestinal inflammation. However, the role of the alteration in the composition and function of the microbiome in this enteropathy remains unclear. It is not clear how much of the dysfunction is attributable to the altered composition and function of the microbiome, but recent evidence that microbiota-directed complementary foods can improve growth suggests that it may make a substantial contribution. The authors had previously found that gut epithelial lesions were key drivers of small intestinal leakiness and microbial translocation among children with SAM [8]. In this study, Mulenga et al. aimed to assess the gut epithelial abnormalities among children with EE and stunting, nonresponsive to nutrition interventions, using confocal laser endomicroscopy, histology, and electron microscopy of the biopsies. Visual images showed leakage from circulation to the gut in 97% of the children. Histology consistently showed gut epithelial micro-erosions, cell-cell adhesion anomalies, and defects in secretory cells (Paneth cells and goblet cells), which may all contribute to impairment of the mucosal barrier function and microbial translocation. These were consistent with those identified in children with SAM.

Site specific incidence rate of virulence-related genes of enteroaggregative Escherichia coli and association with enteric inflammation and growth in children

Comments: Environmental enteric dysfunction (EED) (also referred to as environmental enteropathy, EE) is endemic in LMICs and caused by early and lifelong exposure to environmental enteropathogens including bacteria, parasites, and viruses such as enteroaggregative Escherichia coli (EAEC). This study aimed to estimate the site-specific incidence rates of gene-carrying strains of EAEC and identify their risk factors and the possible associations between EAEC, EED score, and linear growth among 1,705 children aged <24 months enrolled in the MAL-ED birth cohort (South America, sub-Saharan Africa, and Asia). Gene-carrying strains of EAEC were detected by TaqMan Array Cards from stool samples. Infection with the AggR gene-carrying strain of EAEC was the commonest overall (43%). EAEC was strongly associated with poor child growth and development, and changes in intestinal inflammation. Low maternal education, lack of improved floor, and having domestic cattle were  associated with EAEC infection. These findings provide the basis for potential vaccine development aimed at reducing the EAEC burden and therefore EED, with the potential to improve linear growth among children living in impoverished communities in LMICs.

Pathogens associated with linear growth faltering in children with diarrhea and impact of antibiotic treatment: the global enteric multicenter study

Comments: The study uses data from global enteric multicenter prospective matched case-control study of children with moderate to severe diarrhea to quantify the association between childhood diarrhea and linear growth faltering in children aged <24 months at 7 sites in sub-Saharan Africa and South Asia. Previous studies have reported the association between diarrhea disease and linear growth. However, the impact of specific pathogens or recommended antibiotic treatment in this process remains unclear. Interestingly, among 8,077 children with moderate to severe diarrhea across the sites, stunting (defined as height-for-age z-scores [HAZ] < −1) increased from 59% at enrollment to 65% at follow-up (p < 0.0001). This study found that 4 pathogens (Cryptosporidium, typical enteropathogenic E. coli, untreated Shigella, and enterotoxigenic E. coli encoding heat-stable toxin) were associated with linear growth failure. Significant improvement in linear growth was observed among children positive for Shigella treated by the World Health Organization–recommended antibiotics. These findings highlight the importance of timely identification and targeted treatment of diarrhea-causing enteric pathogens among children aged <24 months as a key strategy to promoting linear growth in early childhood in LMICs.

Child stunting starts in utero: growth trajectories and determinants in Ugandan infants

Comments: There are increasing data predominantly from observational studies showing that childhood stunting starts in utero, but they do not account for variation in linear growth between children and a particular age. Using data of 4,528 infants from a Ugandan birth cohort study, the study assessed the relationship between the different growth patterns at birth with pre- and postnatal factors. The researchers found that the stunting occurred before birth and followed 4 distinct growth patterns: chronically stunted, recovery, borderline stunted, and normal (not stunted). Wasting and underweight were observed in all groups and wasting gradually increased among those who were already stunted. The authors argue that disaggregating children’s growth potentials relative to the different risk within each group is key to the design of nutrition interventions. It will be useful to see whether these findings are replicated in other birth cohorts in LMICs.

The relationship between wasting and stunting in young children: a systematic review

Comments: This was a systematic review looking at the relationship between wasting and stunting from studies conducted after 2014 among children under 5 years of age from LMICs. Forty-five studies were included in this review. The key findings were that the peak incidence of both wasting and stunting is between 0 and 3 months. There was also a strong association between the 2 conditions, whereby episodes of wasting lead to stunting, and to a lesser extent, stunting increases the risk of wasting. Children with concurrent stunting and wasting had a higher risk of mortality due to the impact of the dual burden on body composition and should therefore be appropriately risk stratified during treatment. The findings, therefore, challenge the existing status quo of having separate programs and strategies for the different but overlapping conditions. Instead, treatment strategies need to consider the risk of death as paramount to targeting interventions. In addition, while wasting and stunting are driven by common risk factors, targeting interventions by season and population characteristics (sex, and socioeconomic status) might be helpful to reduce the postnatal growth failure.

Consequences

Economic costs of childhood stunting to the private sector in low- and middle income countries

Comments: Childhood stunting has economic consequences including reduced workforce productivity. Income losses of 5–7% in LMICs are associated with reduced workforce productivity as a result of stunting. These estimates reflect the national microeconomic estimates and do not include the private sector, which represents 90% of the workforce in LMICs. This study therefore aimed to quantify the economic burden and financial losses incurred by the private sector as a result of childhood stunting across 123 LMICs by using longitudinal datasets and national surveys. The findings showed that childhood stunting cost the private sector about USD 135.4 billion in sales annually representing 0.01–1.2% national GDP across these countries. Sectors most affected were food sectors, garments, and manufacturing. Monthly losses resulted in unearned losses ranging from USD 700 million to USD 16.5 billion, which could have been used by the stunted individuals to inject into their economies if stunting was eliminated in childhood. Estimates from the longitudinal studies showed that these stunted employees were not high-income earners; hence a slight increase in their earnings was associated with an increase in the access to essential resources. Reducing childhood stunting would therefore increase employees’ human capital, and improve the employees’ employment abilities and the national economy at large. Interestingly, women incurred a higher income penalty from childhood stunting and earned less than men; and the returns for investing in stunting reduction were consistently higher for men across most countries studied. These findings should motivate strong public-private sector partnerships to invest in childhood undernutrition, as this would address a myriad of socioeconomic challenges in LMICs including the gender disparities.

Poor early childhood growth is associated with impaired lung function: evidence from a Ghanaian pregnancy cohort

Comments: Lung health in early childhood is a strong determinant of lung health over the life cycle. Impaired lung function as a result of undernutrition and poor growth is associated with an increased risk of childhood pneumonia and associated mortality. Despite this understanding, evidence on the modifiable risk factors of poor lung health in early childhood has remained scanty. Using the Ghana Randomized Air Pollution and Health Study (GRAPHS) [9, 10] cohort, the authors hypothesized that poor growth was associated with impaired lung function. The children had multiple anthropometric measurements (at birth and 3, 6, 9, 12 months and 4 years), and impulse oscillometry (lung function measurement) at 4 years. The study findings observed an inverse association between airway resistance with weight-for-age at birth (β = -0.90 cmH2O/ L/s, 95% CI: -1.64, -0.16) and HAZ at 4 years of age (β = -0.40 cmH2O/L/s, 95% CI: -0.57, -0.22). Children with persistent stunting had a higher airway resistance compared to normal children in early childhood. This has adverse implications for their lung health in later childhood (increased risk of pneumonia) and adulthood.

Early childhood stunting and later life outcomes: a longitudinal analysis

Comments: This study used data of 6,357 children: 1,334 in Ethiopia, 1,690 in India, 1,609 in Peru and 1,724 in Vietnam to report on the long-term implications of childhood stunting. This showed that children who were severely stunted at 5 years had a 67% probability of being stunted at age 15; thus an indicator of future chronic malnutrition. The consequence for human capital is shown by the strong association with lower grade completion by 22 years and the negative association with cognition in math, language, and reading scores at ages 8, 12, and 15 years and childhood stunting. They also found that access to skilled health personnel during pregnancy, as well as having at least 2 tetanus injections during pregnancy, was strongly associated with reduction in the incidence of stunting at 1 year. This suggests that provision of adequate and integrated maternal and child health services is a key to preventing childhood stunting.

Interventions

Small-quantity lipid-based nutrient supplements for the prevention of child malnutrition and promotion of healthy development: overview of individual participant data meta-analysis and programmatic implications

Comments: While stunting often begins in utero, studies have reported a rapid decline in length-for-age between the 6–24-month period during complementary feeding. This meta-analysis reported the effects of providing lipid-based nutrient supplements to children aged 6–24 months. The prevalence of stunting, wasting, and underweight was 12–14% lower in children who received the small-quantity lipid-based nutrient supplement (SQ-LNS) compared to those who did not. Children who received SQ-LNS also had a 64% lower prevalence of iron-deficiency anemia compared with those in the control group. Gender, an effect modifier, showed stronger effects among girls than among boys, with SQ-LNS reducing the prevalence of stunting among girls by 16 versus 9% among boys. In girls, the overall mean for anthropometric z-scores was higher than in boys, suggesting that they may have a greater potential to respond rather than benefiting from the supplementation. The effect modification results emphasize that targeting during interventions for particular outcomes such as iron status, anemia, and child development should be considered on the basis of population-level socioeconomic status or burden of undernutrition, as some subgroups showed greater potential to benefit from the intervention. These interesting findings provide an opportunity for existing programs to incorporate the use of SQ-LNS in their interventions as a prevention of malnutrition strategy.

A novel intervention combining supplementary food and infection control measures to improve birth outcomes in undernourished pregnant women in Sierra Leone: a randomized, controlled clinical effectiveness trial

Comments: The use of nutritional supplements in single or multiple formulation to treat under-nutrition in pregnancy has yielded modest improvements. The observed modest effect of supplementation on linear growth in newborns suggests that dietary strategies alone are unlikely to reduce the risk of stunting in utero. This trial provided 1,489 undernourished pregnant women with ready-to-use supplementary food alongside azithromycin and testing and treatment for vaginal dysbiosis. The results showed that the recovery rate from undernutrition was 7.2% higher in women receiving the intervention than those receiving standard care (blended corn/soy flour and intermittent preventive treatment for malaria in pregnancy). Maternal weekly weight gain was greater in the intervention group (mean difference 40 g; 95% CI 9.70 to 71.0, p = 0.010) compared to those receiving standard care. However, maternal postpartum mid-up-per arm circumference (MUAC) was not significantly different between the 2 intervention arms. Infants born to mothers in the intervention group were 0.3 cm longer and had MUACs that were 0.1 cm larger than infants born to mothers receiving the standard care. Fewer infant deaths were reported in the intervention group (35; 5.6%) than in the standard care group (53; 8.9%). A mortality benefit was observed in the intervention group within the first 21 days where 13 (1.9%) infants died compared to 28 (4.3%) in the standard care group. While the results of this study emphasize the importance of combining nutritious RUSF with infection prevention strategies during pregnancy, the widespread administration of azithromycin in pregnancy elicits important concerns of emergence of antibiotic-resistant strains. A dilemma presents it-self as to the risks of widespread administration versus the chance to decrease neonatal death by 2.3-fold. Though the intervention is promising, further studies need to be carried out to understand the effects of routine prenatal azithromycin on maternal and infant carriage of resistant organisms.

Do tradeoffs among dimensions of women’s empowerment and nutrition outcomes exist? Evidence from six countries in Africa and Asia

Comments: The study applied Women’s Empowerment in Agriculture Index, an internationally validated measure based on interviews of women and men within the same house-hold, from 6 countries to identify which indicators and dimensions of women’s empowerment are related to dietary and nutrition outcomes in women and children. Results showed that the women’s empowerment score was positively associated with improved child HAZ and better child nutrition. Higher HAZ was associated with women’s empowerment domains where women made more agricultural decisions (p = 0.05), had a higher number of agriculture assets with rights (p = 0.05), made a higher number of credit decisions, and had greater satisfaction with leisure (p = 0.06). A decrease in intrahousehold inequality was associated with a higher likelihood of exclusive breastfeeding and higher HAZ. Women’s empowerment had differential associations with boys’ and girls’ nutritional outcomes. In Bangladesh and Nepal, women’s empowerment showed a negative association with girls’ HAZ compared to boys’ HAZ, while in Cambodia where a larger number of decisions are made by women, there were differential positive associations for girls’ anthropometric outcomes compared to boys and the intrahousehold inequality was associated with higher HAZ and weight-for-age-z score (WAZ) for girls. Interestingly, not all empowerment domains were positively correlated with better nutrition. For instance, improved household dietary diversity required women to invest more time in agricultural activities, which results in increased energy expenditure, with consequences of lower maternal BMI and less time for childcare. These findings are important for nutrition-sensitive programs, emphasizing that empowering women and improving gender equality alone cannot address poor child nutrition. Addressing household wealth and country-level factors are also important.

Perspectives and Policy

Effective nutrition governance is correlated with better nutrition outcomes in Nepal

Comments: There is a gap in understanding whether effective nutrition governance correlates with better anthropometric scores in children. This study therefore aimed to examine this association between effective nutrition governance by using the Nutrition Governance Index (NGI), derived from interviews with 520 government and nongovernment officials and anthropometry, utilizing data from 2 national studies in Nepal: the Policy and Science for Health, Agriculture and Nutrition (PoSHAN) community study and the PoSHAN policy. The study found that this relationship was positive for children over 2 years of age. A higher NGI was positively associated with HAZ and weight-for-height-z score (WHZ) for children >2 years, compared to younger children (HAZ: β   =  0.02, p  <  0.004, WHZ: β   =  0.01, p  <  0.37). A one-point increase in the NGI was significantly associated with a 12% increase in HAZ and a 4% increase in WHZ in older children aged > 24 months. The study findings highlight the crucial role of effective management of policy-based programming and resources in improving child nutrition and growth. Measuring NGI may be used as a tool to help governments monitor their progress in implementing child nutrition policies

Nutrition modeling tools: a qualitative study of influence on policy decision making and determining factors

Comments: While nutrition modeling tools (NMTs) have generated evidence needed for policy decisions and program implementation in LMICs, there is a gap on how the evidence they generate is applied and any influence it has had on policy or program decisions. In this study, 109 interviews were conducted with informants from 30 LMICs to explore how NMTs influence policy and factors that lead to this. Findings showed that NMTs were mostly applied by international organization to inform national government decision making. Equipping government officials and consumers to have a better understanding of the cycle of evidence generation, the application of evidence to inform policy and the implementation and uptake of policies for nutrition is vital. Creating an environment where stakeholders and government partners are more confident to interpret and present modeling data built a solid case for continued use of modeling locally and increased sense of ownership. Local leadership in evidence generation also helped put the local agenda on the forefront with limited influence of  external agendas that would seek to overshadow national interests. There is need for further studies to understand how NMTs can be better applied in the future in terms of better planning for evidence generation, resources to support NMT application, modification, and new tool development as well as supporting local stakeholders’ participation and local adaptation of evidence.

Revisiting the stunting metric for monitoring and evaluating nutrition policies

Comments: The authors of this article question the accuracy of using stunting as a metric for measuring child undernutrition in India. They proceed to caution Indian policymakers regarding the use of stunting metrics to measure the effectiveness of interventions in the next phase of India’s nutrition program PoSHAN Abhiyaan 2.0. Firstly, the mothers in the Indian Multicenter Growth Reference Study (MGRS) were much taller than the average population. The stunting metric incorporates intergenerational components of child growth, thus children born to short mothers determined by their own nutrition insults are more likely to pass that down to their offspring. Current policies being implemented cannot thereby change the past nutrition and environmental insults that played a key role in determining maternal height. Secondly, they argue that calculating India’s stunting prevalence using MGRS will, to an extent, result in an overestimation of child undernutrition. The MGRS focuses on the analysis of growth patterns of a specific population that is under an ideal environment and does not determine whether the pattern would be homogenous if compared to the children in poor environments at the same age at the same point in time. They continue to argue that adjusting for maternal height would not only grossly underestimate the effect of on-going exposures to deficient conditions on a child’s height but would also mean re-adjustment of multiple indicators of child growth and development that are deter-mined by genetic and environmental factors. Changing how stunting prevalence is calculated for specific populations compared to the rest globally will not only cause confusion but would hamper global efforts to achieve sustainable development goals in relation to reduction of child undernutrition.

References

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