Elsevier

The Lancet

Volume 399, Issue 10336, 30 April–6 May 2022, Pages 1741-1752
The Lancet

Series
Effects of early-life poverty on health and human capital in children and adolescents: analyses of national surveys and birth cohort studies in LMICs

https://doi.org/10.1016/S0140-6736(21)02716-1Get rights and content

Summary

The survival and nutrition of children and, to a lesser extent, adolescents have improved substantially in the past two decades. Improvements have been linked to the delivery of effective biomedical, behavioural, and environmental interventions; however, large disparities exist between and within countries. Using data from 95 national surveys in low-income and middle-income countries (LMICs), we analyse how strongly the health, nutrition, and cognitive development of children and adolescents are related to early-life poverty. Additionally, using data from six large, long-running birth cohorts in LMICs, we show how early-life poverty can have a lasting effect on health and human capital throughout the life course. We emphasise the importance of implementing multisectoral anti-poverty policies and programmes to complement specific health and nutrition interventions delivered at an individual level, particularly at a time when COVID-19 continues to disrupt economic, health, and educational gains achieved in the recent past.

Introduction

Massive inequalities in the distribution of wealth, both between and within countries, are a key challenge to sustainable development.1 Despite progress in the alleviation of poverty in most parts of the world over the past three decades, wealth inequalities still exist, and several low-income countries have seen the incomes of the bottom 40% stagnating, or even decreasing.2, 3 In a time trend analysis of 83 countries, the global average Gini index—weighted by national population size—increased from 36·7 in 2000 to 40·8 in 2015. This finding indicates that the average person was living in a country where inequality was on the rise.4

Addressing inequality is at the core of the Sustainable Development Goals5 target of leaving no one behind.6 Economic inequality is not only important per se, but it is also a major driver of health status, as is emphasised by initiatives aimed at tackling the social determinants of health.7 In addition to how the poorest communities are at increased risk of illness and malnutrition, inequality affects the health of entire populations. Social gradients in health are ubiquitous, with stepwise increases in illness and mortality down the socioeconomic spectrum.8

There is ample literature on the effect of poverty during the life course in high-income societies. Birth cohort analyses, from countries such as the UK, New Zealand, USA, and Norway, point to the lifelong effects of material and psychosocial exposures on health and human capital.9 By contrast, the literature from low-income and middle-income countries (LMICs) on such topics is scarce. Nevertheless, many (if not most) children currently living in LMICs experience suboptimal nurturing care,10, 11 an innovative concept that encompasses child health, nutrition, learning, relationships, security, and safety. These five components of nurturing care are largely determined by poverty; a “cause of the causes”12 of poor health and development. Exposure to adversity in early life,9, 13 for which poverty is a proxy measure, is postulated to be a major driver of adequate nurturing care and of its consequences on human capital.

Key messages

  • Data from low-income and middle-income countries (LMICs) substantiate the negative effects of early-life poverty on the survival, nutrition, and cognitive development of children and adolescents

  • Analyses of long-term birth cohorts in LMICs show that early-life poverty is strongly and inversely associated with human capital indicators, such as adult height, achieved schooling, and intelligence

  • By contrast, some risk factors for non-communicable diseases, including overweight and signs of metabolic syndrome in adults, are less common in men, but not in women, exposed to early-life poverty than in the rest of the population

  • Broad and multisectoral anti-poverty policies and programmes need to be urgently strengthened to offset the impact of COVID-19 on poverty and to promote the health and development of children and adolescents, both in the short term and long term

The first paper in this Series used evidence from longitudinal studies to consider conditions of survival, growth, disability, and education in world regions and their effects on crucial periods in the lifecycle before adulthood that build the foundation for human capital.11 In this second Series paper, we review data on key conditions related to human capital in children, adolescents, and adults, and analyse how early-life poverty contributes to their enduring prevalence throughout the life course. Using data from 95 national surveys in LMICs, we assess the presence and magnitude of social gradients in the health, nutrition, and cognitive development of children and adolescents, reflecting the accrual of human capital. Additionally, we use data from six large, long-running birth cohorts in LMICs to explore the long-term associations between early-life poverty and health and human capital outcomes in adulthood. In both sets of analyses, we use indicators related to the constructs of nurturing care and of human capital, including survival, health, nutrition, and cognition. We also report on selected conditions that affect an individual's ability to contribute to society, including stunted height14 and obesity15 in adulthood, teenage motherhood,16 and psychological symptoms.17 This information informs consideration of interventions, intersectoral approaches, and policies, which are addressed in the third18 and fourth19 papers of this Series.

Section snippets

An analysis of 95 national surveys

The analyses of national surveys addressed the following five outcomes related to human capital in children and adolescents: mortality rate and prevalence of growth stunting in children younger than 5 years, not being on track for development in children aged 3–5 years (based upon the Early Childhood Development Index),20 teenage motherhood (the proportion of women aged 20–29 years who had become mothers before age 20 years), and completion of primary school in girls aged 15–19 years. Teenage

Effects of women's empowerment

Early-life poverty is a comprehensive indicator of early child adversity,13 for which plentiful data are available. Family wealth is used as the main marker for early-life adversity in our analyses; however, there are other important dimensions of adversity, including women's empowerment, which is associated with mortality rates and prevalence of growth stunting in their children younger than 5 years (figure 2).

We used the Survey-based Women's emPowERment (SWPER) global index39 to categorise

Analyses of six birth cohort studies

To assess how strongly exposure to early-life poverty predicted adult health and human capital outcomes in LMIC contexts, we reanalysed data from the six longest-running births cohorts in LMICs, the COHORTS consortium, which had at least 1000 participants at recruitment and frequent visits in early life (table 3).41 All cohorts were population-based, yet socioeconomic inequality was less marked in the urban poor cohort from Soweto, South Africa, and in the rural poor cohort from Guatemala than

Conclusions and implications

Our analyses provide considerable documentation of pervasive social gradients in the survival, health, nutrition, and cognitive development of children, as well as in teenage motherhood and in girls' education. The analyses of 95 national surveys confirmed the importance of gross domestic product in predicting levels of the five outcomes under study. Within countries, we were able to document consistent, stepwise social gradients in human capital indicators in children and adolescents from

Search strategy and selection criteria

For analyses of the associations between poverty and health, nutrition, and development outcomes in children and adolescents, we searched the comprehensive Countdown to 2030 survey database, which is also included in WHO's Health Equity Monitor website. The Countdown to 2030 database includes over 450 publicly available demographic and health surveys from over 120 countries. We identified 440 nationally representative surveys with publicly available data from 127 countries, from which we

Declaration of interests

REB serves on the Board of Vitamin Angels, a non-profit charitable organisation supporting maternal and child nutrition services in LMICs. AS and ADS report grants from Bill and Melinda Gates Foundation. AS reports grants from the Wellcome Trust. ZAB reports grants from the International Development Research Centre (reproductive, maternal, newborn, child, and adolescent health in conflict settings: case studies to inform implementation of interventions) and Countdown to 2030–UNICEF. All other

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