Discussion

This study provides a comprehensive assessment of the prevalence and temporal trends of PEM among children under 5 years of age in WHO SEAR countries using data from the Global Burden of Disease Study 2023. Our findings demonstrate a substantial overall decline in prevalence, incidence, deaths and DALY count between 1990 and 2023. Despite these encouraging regional improvements, the burden of PEM remains considerable in several countries, with substantial variation in prevalence levels and temporal trends across nations. In addition, the prevalence rates of PEM remain disproportionately high among older infants and young children, highlighting important age-related disparities in PEM prevalence.

The reduction in prevalence counts and prevalence rates per 100 000 population across countries over the years indicates a genuine improvement in the burden rather than merely a demographic artefact of changes in population size or age structure. This is particularly relevant given that several SEAR countries have experienced substantial declines in total fertility rates over the past three decades, which could otherwise account for part of the reduction in absolute case counts alone. The steady decline in PEM prevalence across SEAR over the past three decades may be associated with broader improvements in socio-economic conditions, maternal education, child survival programmes and expanded access to primary healthcare. Global analyses have consistently shown that improvements in education and income, along with reductions in fertility, are associated with declines in child undernutrition^{(Reference Headey, Hoddinott and Park13)}. The sharper decline observed after 2010 may partly reflect the cumulative impact of strengthened nutrition-specific and nutrition-sensitive interventions implemented across the region, alongside global initiatives such as the Scaling Up Nutrition (SUN) movement and Sustainable Development Goals (SDG)⁽¹⁴⁾.

The observed ecological association between an increase in the SDI and a decline in PEM prevalence reinforces the importance of broader development factors in shaping child nutrition outcomes. Previous GBD analyses have similarly demonstrated strong inverse relationships between SDI and DALY attributable to child undernutrition. However, the variability in slopes across countries suggests that economic growth alone is insufficient to reduce PEM; governance quality, equity in service delivery and health system performance likely play important mediating roles^{(Reference Zhang, Zhang and Pu2,Reference Nallari and Griffith15)} . In addition to socio-economic and health system factors, improvements in environmental conditions across the region, including expanded access to safe drinking water, improved sanitation facilities and reduced open defecation, likely contributed to the observed decline in PEM prevalence. Improved water, sanitation and hygiene (WASH) help reduce enteric infections, thereby improving nutrient absorption in young children. However, as an ecological analysis, this study cannot establish causal relationships between these factors and the observed decline in PEM prevalence; the associations described here should be interpreted as plausible contributors rather than confirmed determinants.

Although all countries experienced an overall decline in PEM burden, the magnitude and pace of reduction varied substantially across SEAR. This pattern is consistent with other global trends, where mortality and DALY have declined since 1990, but the burden remains higher. Similar heterogeneity has been documented in global undernutrition trends, where neighbouring countries with comparable income levels show markedly different trajectories due to differences in policy prioritisation and implementation capacity^{(Reference Zhou, Li and Cai16)}. India and Bangladesh continue to contribute the largest absolute number of cases due to their large population sizes. Despite sustained reductions, India accounts for a substantial share of the global burden of child undernutrition^{(1,Reference Headey, Hoddinott and Park13)} . This underscores the need for intensified, equity-focused strategies targeting high-risk districts and marginalised populations. In contrast, Timor-Leste’s slower progress may reflect persistent food insecurity, fragile health systems and heightened vulnerability to economic and climatic shocks, factors recognised as important drivers of undernutrition globally⁽¹⁷⁾. The plateau observed in Bangladesh during 2002–2010 and the slower decline in Indonesia in recent years mirror findings from other low-middle-income country settings, where economic transitions do not always translate immediately into improvements in child nutrition outcomes without nutrition-sensitive interventions^{(Reference Ruel and Alderman18)}.

The highest prevalence observed among children aged 6–23 months aligns with well-established evidence identifying the complementary feeding period as the most critical window for growth faltering^{(Reference Dewey and Adu-Afarwuah19)}. During this stage, children experience increased nutritional requirements while also facing greater exposure to contaminated complementary foods and heightened susceptibility to infections, which interact bidirectionally with undernutrition^{(Reference Scrimshaw, Taylor and Gordon3,Reference Dewey and Adu-Afarwuah19)} . Growth faltering often begins in utero and accelerates during the first 2 years of life, with long-term consequences for cognitive development, educational attainment and adult productivity^{(Reference Hoddinott, Behrman and Maluccio20)}. The persistent burden observed among children aged 2–4 years in some countries may reflect cumulative nutritional deficits and continued exposure to adverse environmental exposures.

SEAR countries have undergone rapid urbanisation and dietary transitions over the past three decades. While reductions in severe wasting have been observed, shifts towards energy-dense, nutrient-poor diets have contributed to the emerging double burden of malnutrition^{(Reference Popkin, Corvalan and Grummer-Strawn21)}. The coexistence of persistent undernutrition and rising childhood overweight highlights the complexity of ongoing food system transitions in the region. The slower decline observed during 2020–2023 may partly reflect the indirect effects of the COVID-19 pandemic. Global modelling studies have suggested substantial increases in child wasting and disruptions in essential nutrition services during the pandemic period^{(Reference Headey, Heidkamp and Osendarp22)}. Disruptions in food supply chains, economic contraction and reduced utilisation of health services may therefore have slowed progress in several SEAR countries.

The main strength of this study is the use of standardised and comparable estimates from GBD 2023, enabling long-term and cross-country comparisons of the burden of PEM. In addition, the use of Joinpoint regression allowed the identification of inflection points in temporal trends, providing insights into changes in the pace of decline over time. However, several limitations should be acknowledged. GBD estimates rely on modelling techniques that integrate heterogeneous data sources, which may introduce uncertainty, particularly in data-sparse settings and countries with limited vital registration and surveillance systems. Furthermore, the use of ICD-based definitions for PEM may underestimate subclinical or community-level undernutrition. Finally, the ecological associations observed between SDI and PEM prevalence should not be interpreted as causal, and SDI may not fully reflect within-country equality, as it is an aggregate developmental index.

Our findings highlight the need to sustain and strengthen integrated nutrition strategies across SEAR countries. Expanding nutrition-specific interventions, including promoting exclusive breast-feeding, complementary feeding counselling, micronutrient supplementation and community-based management of acute malnutrition, remains essential^{(Reference Dewey and Adu-Afarwuah19)}. At the same time, scaling up nutrition-sensitive interventions such as improvements in sanitation, women’s education, poverty reduction and food security programmes will be critical to address the underlying determinants of child undernutrition⁽¹⁴⁾. Targeting high-burden districts and vulnerable groups may help reduce persistent inequities. Strengthening nutrition surveillance and the resilience of health systems, particularly during public health emergencies, will also be important to sustain progress^{(Reference Headey, Heidkamp and Osendarp22)}. Lessons from countries that have achieved more rapid declines in PEM may help inform effective policy implementation across the region.