A Review of the Evidence Linking Child Stunting to Economic Outcomes Mark E Mcgovern,1,2 Aditi Krishna,3,4 Victor M Aguayo,5 and SV Subramanian3,4*

International Journal of Epidemiology, 2017, 1–21 doi: 10.1093/ije/dyx017 Original article

Original article A review of the evidence linking child stunting to economic outcomes Mark E McGovern,1,2 Aditi Krishna,3,4 Victor M Aguayo,5 and SV Subramanian3,4*

1CHaRMS: Centre for Health Research at the Management School, Queen’s University Belfast, 2UKCRC Centre of Excellence for Public Health (Northern Ireland), 3Harvard Center for Population and Development Studies, 4Department of Social and Behavioral Sciences Harvard T.H. Chan School of Public Health and 5United Nations Children’s Fund (UNICEF), Nutrition Section, Programme Division, New York

*Corresponding author. Harvard Center for Population and Development Studies, 9 Bow Street, Cambridge 02138, MA, USA. E-mail: [email protected]

Accepted 17 January 2017

Abstract Background: To understand the full impact of stunting in childhood it is important to consider the long-run effects of undernutrition on the outcomes of adults who were affected in early life. Focusing on the costs of stunting provides a means of evaluating the economic case for investing in childhood nutrition. Methods: We review the literature on the association between stunting and undernutrition in childhood and economic outcomes in adulthood. At the national level, we also evaluate the evidence linking stunting to economic growth. Throughout, we consider randomized controlled trials (RCTs), quasi-experimental approaches and observational studies. Results: Long-run evaluations of two randomized nutrition interventions indicate substantial returns to the programmes (a 25% and 46% increase in wages for those affected as children, respectively). Cost-benefit analyses of nutrition interventions using calibrated return estimates report a median return of 17.9:1 per child. Assessing the wage premium associated with adult height, we find that a 1-cm increase in stature is associated with a 4% increase in wages for men and a 6% increase in wages for women in our preferred set of studies which attempt to address unobserved confounding and measurement error. In contrast, the evidence on the association between economic growth and stunting is mixed. Conclusions: Countries with high rates of stunting, such as those in South Asia and sub- Saharan Africa, should scale up policies and programmes aiming to reduce child undernutrition as cost-beneficial investments that expand the economic opportunities of their children, better allowing them and their countries to reach their full potential. However, economic growth as a policy will only be effective at reducing the prevalence of stunting when increases in national income are directed at improving the diets of children,

VC The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] 2 International Journal of Epidemiology, 2017, Vol. 0, No. 0 addressing gender inequalities and strengthening the status of women, improving sanitation and reducing poverty and inequities.

Key words: Stunting, productivity, economic growth, early childhood investment

Key Messages

• Undernutrition in childhood, primarily as measured by stunting or height-for-age, is consistently linked to worse economic outcomes as an adult • Although lower than results from the two existing nutrition intervention studies which track affected children across the life course, quasi-experimental estimates of the impact of height on wages are substantial, the median being 4% per CM for men and 6% for women • Cost benefit analyses of childhood nutrition interventions typically find them to be cost beneficial or highly cost beneficial • At the country-level, there is little evidence that short-run increases in GDP can achieve meaningful reductions stunting prevalence, if increases in national income are not directed at improving the diets of children, addressing gender inequalities and strengthening the status of women, improving sanitation and reducing poverty and social inequities • Few studies examine the impact of undernutrition on economic growth, but spillover effects of health on labor markets and capital accumulation may be substantial • Countries facing high stunting prevalence, such as those in South Asia and sub-Saharan Africa, should consider resources used to improve childhood nutrition as cost-beneficial investments in the wellbeing of their populations and their economies

Introduction there remain areas where the evidence is sparse. In particu- There is growing interest in the long-run impact of child- lar, whereas there is an evidence base linking stunting to hood conditions among both researchers and policy mak- short-run outcomes in childhood such as cognition and edu- ers, in part because there is mounting evidence that early cational attainment, evidence on the long-run effects is life environments impact on a variety of later life outcomes, more limited. For example, cost-benefit analyses of nutri- including health, nutrition, cognition and mortality. In low- tion interventions and reviews of potential wage losses and middle-income countries, the role of childhood growth associated with early life undernutrition tend to rely on cali- restriction and stunting has been attracting particular atten- brated estimates of returns to schooling, and the fact that tion1 which is likely a reflection of the fact that indicators children who are stunted have lower levels of educational of progress to address child undernutrition were included in attainment, rather than measures of the direct association 5 the Millennium Development Goals;2 their inclusion in the between stunting and adult outcomes. post-2015 Sustainable Development Goals; and the sub- It is important for policy makers to have accurate infor- optimal progress in many countries at achieving improve- mation on the long-run economic benefits associated with ments in child nutrition.3 For example in South Asia, rates investments in child nutrition, particularly in contexts in of childhood stunting remain at 38% despite rapid eco- which government resources are scarce or there is a high nomic growth in some countries such as India.4 Advocacy opportunity cost of funds due to attractive investment op- for inclusion of child nutrition targets in the Sustainable tions in other domains such as education and infrastruc- Development Goals appeals to an emerging understanding ture. If high-quality evidence demonstrates economic of the consequences of failure to address early life undernu- returns to reducing child stunting, this will make it easier trition and the consequent impact of restriction of growth to compare returns on investment with these alternatives and developmental potential on both individuals and soci- on the basis of formal cost-benefit analyses.6 ety as a whole. Incorporating markers of child nutrition The aim of this paper is to address this knowledge gap into the new round of global development goals could by providing a comprehensive review of the evidence on the prove beneficial in lowering stunting prevalence, not least long-run economic impact of child undernutrition, mostly by presenting an opportunity to build commitments to ad- as measured by the direct association between stunting and dressing this issue as part of a global policy platform.1 later life outcomes. There are other overview papers dealing However, despite the policy focus on reducing stunting, with child undernutrition, but they either do not focus on International Journal of Epidemiology, 2017, Vol. 0, No. 0 3 long-run economic outcomes, or else focus on a subset of welfare, poverty; and the following measures of childhood the literature. In contrast, we provide a comprehensive re- undernutrition: stunting, child development, growth review of intervention studies that track cohorts of individu- tardation, growth trajectory, linear growth, linear growth als who received nutritional supplements in early childhood retardation, growth faltering, growth failure, early life into adulthood, but also cover prospective cohorts where growth failure, child undernutrition, child malnutrition, we have data on the same individuals across the life course child nutrition. Search terms are shown in Box 1. (some of whom may have been stunted, but where there Combinations and variations of these keywords were was no randomized intervention), papers which adopt a also included in the search using the wildcard operator, quasi-experimental approach relying on natural experi- and we supplemented the search using the references of the ments (which affected nutritional intake in childhood) and observational cross-sectional data where we are able to measure the association between adult height and adult BOX 1. Search criteria wages. After reviewing the individual-level correlates of Databases searched: stunting, we also discuss cost-benefit analyses of nutritional PubMed, Econlit. interventions and the aggregate relationship between stunting and economic growth at the country level. This is rele- Key terms: vant because there may be spillover effects of child (wages, income, salary, pay, earnings, productivity, undernutrition on economies and society that would not be capital, resources, work, employment, industry, hours captured by simply adding up individual-level estimates. In worked, occupation, labor, sector, job, socioeconomic, addition, examining whether economic growth can be ex- savings, economic, returns, make ends meet, welfare, pected to successfully reduce stunting prevalence can pro- poverty) vide an indication as to which channels are best targeted to and achieve childhood nutrition targets. The goal of reviewing these estimates is to support pol- (stunting, child development, growth retardation, icy makers in evaluating whether nutrition programmes growth trajectory, linear growth, linear growth retard- are an efficient use of public funds, and where programmes ation, growth faltering, growth failure, early life growth for reducing child stunting rank in terms of return on in- failure, child undernutrition, child malnutrition, child vestment. We conclude the paper with a discussion on the nutrition). implications of our findings for countries facing high prevalence of child undernutrition. studies we located, as well as the citations of these studies obtained from Google Scholar. We identified 29 key sum- Methods mary papers that provided conceptual or background ma- We conducted a literature search for studies published up terial related to research on the long-run economic effects to July 2015 that examined whether childhood stunting or of childhood stunting or undernutrition. We also identified other measures of undernutrition were associated with eco- 21 prospective studies (some of which were based on simi- nomic outcomes in later life. We excluded studies that lar underlying data and some of which contained data examined outcomes in childhood (such as education or test from more than a single country) from 14 cohort studies scores) or other non-economic outcomes in adulthood and seven intervention studies, along with five natural ex- (such as health or cognition). We also restricted our atten- periment papers which retrospectively tied individuals to tion to papers that used measures or proxies of undernutri- periods of adversity argued to be related to undernutrition tion in childhood as exposures, rather than broad measures in early life. We supplemented these prospective studies of early life conditions such as socioeconomic status or and review papers with cross-sectional research that exam- health. We did not include studies that only examined ex- ined the relationship between adult height and adult eco- posures in utero, as the literature focusing on these areas nomic outcomes. We identified 10 quasi-experimental has been covered elsewhere.7–11 We conducted our litera- instrumental variables papers in this area in which we were ture search using the Pubmed and Econlit databases for able to extract a coefficient measuring the association be- keywords in abstracts and titles related to the following tween a 1-cm change in height and the percentage change economic outcomes: wages, income, salary, pay, earnings, in wages. A further 17 studies used linear regression to productivity, capital, resources, work, employment, indus- examine the wage premium related to height but did not try, hours worked, occupation, labour, sector, job, socioe- attempt to adjust for unobserved confounding or measure- conomic, savings, economic, returns, make ends meet, ment error. We identified another 30 studies that provided 4 International Journal of Epidemiology, 2017, Vol. 0, No. 0 evidence on the relationship between adult height and measure stunting or height contemporaneously in child- other adult economic outcomes. hood but track cohort members into adulthood, and evi- An important methodological issue for this literature is dence from natural experiments, which retrospectively tie how child undernutrition is measured. The papers we con- individuals to events associated with periods of undernutri- sider can be roughly divided into three categories. In the tion in early life. Third, we provide a comprehensive as- first set, undernutrition in early life is measured contem- sessment of the literature from cross-sectional data that poraneously during childhood, almost always using height- documents the relationship between height in adulthood for-age, and then, in a subsequent iteration of the study, and wages, comparing estimates from observational and the adult outcomes of these children are observed. Low quasi-experimental approaches that are designed to correct height-for-age is generally used to indicate failure to reach for measurement error and potential unobserved con- growth potential due to inadequate net nutrition, and is founding. Fourth, we discuss how cost-benefit analyses of often dichotomized into an indicator for stunting (being 2 nutrition interventions have been conducted, and provide standard deviations or more below the reference height- an overview of these findings. Finally, we consider whether for-age, typically the World Health Organization growth there is evidence linking the prevalence of stunting to ag- 12 standard). In the second set, we observe the adult out- gregate effects on economic growth, and whether eco- comes of individuals for whom we do not have a direct nomic growth in turn affects child undernutrition. We measure of early life undernutrition, but we know that conclude in the discussion section with a summary of the some of these individuals were exposed to an event such as strength of the evidence linking childhood stunting and a famine during their childhood. In the third set, we ob- undernutrition to adult economic outcomes, as well as a re- serve the adult outcomes of individuals and their adult view of the implications of these findings for countries heights. In order to emphasize the importance of taking with high rates of stunting, particularly those in South into account how childhood undernutrition was measured, Asia. in Tables 2, 3 and 4 we note the exposure used in each study in column 6. In Tables 5 and 6 we note the age at which the exposure (adult height) was measured in Findings column 9. Review papers Each of these approaches to measuring exposure to early life undernutrition has its own advantages and disad- Table 1 presents the key background papers that cover vantages, and we return to a discussion of the measure- topics outlining the rationale for investing in nutrition in 15–25 ment issue as part of the Appendix. It is important to note, early childhood, and details of the long-term follow-up however, that the underlying assumption behind the ap- of a cohort who received a nutrition intervention in 26 proach of studying the link between adult height and adult Guatemala, which has featured heavily in the literature. outcomes is that height or length in childhood is suffi- These papers also provide a summary of the potential path- ciently predictive of adult height for the latter to provide ways linking stunting and undernutrition to economic out- an adequate proxy for childhood undernutrition. This hy- comes, the interaction of nutrition programmes with other pothesis has been assessed in prospective cohort studies childhood interventions,27 the relationship between nutri- that follow children from birth into adulthood. In the tion, productivity and economic growth,18,28,29 economic British 1958 National Child Development Study (NCDS) returns to other interventions targeted at child and maternal and the 1970 British Cohort Study (BCS), healthier, better- health in low- and middle-income countries,30 global losses nourished children were substantially more likely to go on associated with malnutrition,31 the use of height as a marker to reach their height potential.13 Moreover, a recent review for human welfare,32–36 child growth and development,37 of data from five birth cohorts in low- and middle-income trends in the global prevalence of stunting3,38 and the effect- countries found that the correlation coefficient relating iveness of interventions to reduce child and maternal under- length at 12 months with adult height ranged from 0.43 to nutrition.30,39–42 0.49.14 The literature thus supports the hypothesis that, within a given population, growth failure in childhood is Evidence from intervention studies, prospective predictive of reduced attained stature in adulthood. cohorts and natural experiments The rest of this paper is structured as follows. First, we begin by reviewing existing summary papers. Second, we We were able to locate two long-term follow-ups of inter- present an overview of estimates of the association be- vention studies conducted in Guatemala and Jamaica. The tween stunting and subsequent outcomes from long-run former, the Institute of Nutrition of Central America and follow-ups of intervention studies, prospective studies that Panama (INCAP) study,43,44 allocated nutritional International Journal of Epidemiology, 2017, Vol. 0, No. 0 5

Table 1. Key summary papers on the economic consequences of childhood stunting and undernutrition

Author Year Focus

Alderman 2010; 2013 Summary of pathways linking stunting to economic outcomes and associated costs of malnutrition Alderman et al. 2014; 2015 Integration of nutritional interventions with other childhood programmes, programme design and estimation of economic returns Behrman et al. 1993 Evidence on nutrition and productivity Behrman 2009 Summarizes follow-up study in Guatemala and benefit-cost analyses for early life nutritional interventions Behrman et al. 2017 Potential health and economic benefits of improving early childhood nutrition, long-term benefits, and cost-benefit analysis Bhutta et al. 2008; 2013 Interventions to address undernutrition and micronutrient deficiencies in women and children Dewey and Begum 2011 Overview of the long-run impact of stunting Fogl 1994 The role of physiology in economic growth Halim et al. 2015 Economic impacts of 23 reproductive, maternal, newborn and child health (RMNCH) interventions, published in 29 empirical studies Hoddinott et al. 2013 Functional consequences of stunting, summarizes literature around each of the links in the life cycle, and estimates benefit-cost ratios for a plausible set of nutritional interventions to reduce stunting Horton and Steckel 2011 Estimates of the economic losses from malnutrition worldwide Hu¨ bler 2016 Summarizes relationship between height and wages from an economic perspective, with summary of recent evidence Martorell 2005 Overview of design and findings from the Guatemala Institute of Nutrition of Central America and Panama (INCAP) Study Norgan 2000 Physiological perspective on the long-term economic consequences of growth retardation in children and adolescents Schultz 2003 Summarizes key methodological challenges associated with estimating returns to height and human capital from an economic perspective Steckel 1995; 2009; 2013 Overview of literature which uses height as a measure of human welfare Strauss and Thomas 1998 Discusses our understanding of the interrelationships between health, nutrition and economic development Sudfeld et al. 2015 Association of child growth with child development Stevens et al. 2012 Summary of global prevalence and trends in child stunting UNICEF 2013 Reviews background studies, current prevalence of malnutrition across various indicators, case studies in improving nutrition, and global initiatives Victora et al. 2008 Associations between maternal and child undernutrition with human capital and adult health in low-income and middle-income countries World Bank 2006; 2007; 2010 Reviews the effectiveness of nutrition interventions and rationale for investment in early child development supplements to pregnant women and infants in two found that a 1 standard deviation increase in height-for- Guatemalan villages in the late 1960s and 1970s. Two age was associated with a 21% increase in household per nearby control villages did not receive the supplements. A capita expenditure and a 10% point decrease in the prob- number of studies that follow the children included in the ability of reporting living in poverty at ages 25–42.49 A se- INCAP intervention into adulthood find effects of receiv- cond intervention study was conducted in Jamaica in the ing the nutritional supplements on economic outcomes, mid 1980s.50 A group of undernourished children were including productive capacity, wages, expenditure and the randomly allocated to groups that included a nutrition sup- probability of living in poverty.45–48 Studies that use inten- plementation intervention, psychosocial stimulation, com- tion to treat analysis (ITT) find that men who received the bined nutrition and stimulation, and a control group. supplements as children had, on average, a 46% increase These children were subsequently followed up with in in wages.43 The association was not found to be statistic- 2007–08 at age 22. Those who received the stimulation ally significant for women. An instrumental variables ana- and combined intervention were found to have increased lysis using variation in height-for-age Z score at age 2 earnings by 25% relative to the control group. The associa- years predicted by receipt of the nutritional supplement, tion between the nutritional supplement alone and wages 6 International Journal of Epidemiology, 2017, Vol. 0, No. 0

was not statistically significant. These two studies, papers from which are shown in Table 2, are the only two long-

0.038) term follow-ups to nutrition interventions that we are þ aware of. We located five natural experiment papers which examined the long-run economic outcomes of cohorts exposed to conditions in infancy that were likely to have resulted in undernutrition for those affected. The benefit of this natural experiment approach is that the events of interest can often reasonably be considered as unexpected shocks which affect nutritional status in a way that is unrelated to unobserved characteristics of these individuals, thereby

follow-up was signiﬁcantly greater in subjects from treated villages of both sexes ( increased household per capita expenditure (21%) and a lower probability ofpoverty living (10 in percentage points) reducing concerns about unobserved confounding. Three Intervention increased earnings by 25% Maximum oxygen consumption (VO2max) at 46% increase in average wages for men 1-SD increase in HAZ was associated with of these events are the famine in China in 1959–61,51 the war-related famine in Greece (1941–42) and the war- related food crisis in Germany (1944–48).52,53 Although the Dutch ‘Hunger Winter’ of 1944–45 also features in this literature, we are not aware of any study that examines the economic outcomes of survivors.54 An additional paper considers exposure to rainfall in Indonesia in early life, which is positively associated with higher crop yields, stature, and thus likely better nutritional status, and found growth-stunted toddlers periment during gestation and the preschool years periment during gestation and the preschool years age 2 years that exposure was significantly associated with higher scores on asset indices (a proxy for household wealth) for women, but was not statistically significant for men.55 Survivors of the Chinese famine in 1959–61 were found to 1986–87 Psychosocial stimulation to 1969–77 Height-for-age Z (HAZ) score at 1969–77 Nutritional supplementation ex- 1969–77 Nutritional supplementation ex- have lower labour supply and reductions in some measures of income compared with surrounding cohorts who were not in infancy during the famine. Those in infancy during the Greek famine of 1941–42 were found to have lower occupational status when followed up on using national census data. In contrast, there was no evidence of adverse economic effects of exposure to the German food crisis in treat strumental variables/ treatment on treated tion to treat tion to treat childhood, although this study found that those exposed in Cluster, randomized, inten- utero were adversely affected. Kesternich et al. (2014) find that having lived in a European country affected by conflict during World War II was associated with lower wealth in later life for those among the bottom two socioeconomic status (SES) tertiles in childhood, with poor nutrition being one potential channel for this result.56 A final study exam- Institute of Nutrition of Central America and Panama ined the relationship between height and adult outcomes using an approach based on sibling comparisons in Sweden, which has the benefit of allowing all observed and unobserved factors constant within families to be con- Guatemala INCAP: Guatemala INCAP Cluster, randomized, inten- trolled for.57 This study found large returns to height in the form of increases in wages and occupational status.58

2008; Results from these studies are shown in Table 3. 2010 2005; 2013 Guatemala INCAP Cluster, randomized, in- Alderman et al. (2006) use an instrumental variables ap- 1995 et al. 2014 Jamaica Jamaican Study Randomized, intention to et al. 1996; et al. et al. proach and report that drought exposure in childhood in Intervention studies on the economic consequences of childhood stunting and undernutrition et al. et al. Zimbabwe led to height-for-age Z score 1.25 standard et al. deviations (SD) lower, which was estimated to be associ- Hodonnitt Martorell Haas Hodonnitt Haas Table 2. AuthorsGertler Location Data Design Year Exposure Result Hoddinott ated with a 14% reduction in lifetime earnings; however, International Journal of Epidemiology, 2017, Vol. 0, No. 0 7

this figure is calculated from calibrated effects of schooling on earnings, rather than a direct association observed in 59 1.111 the data, and is therefore not included in Table 3. Alderman et al. (2006) conduct a similar analysis for Tanzania.60 0.296 and only, not for those Evidence from prospective studies

in utero Next we present evidence from prospective studies, which have the benefit of measuring stunting or undernutrition in early life rather than relying on adult height, but do not generally deal with measurement error or unobserved confounding. Most of these studies use measures of childhood height collected as part of established cohort studies in the UK, Brazil and the Philippines.61–64 One study that does rate increase; for the 1959 cohort,agrarian the income annual decreased per by capita approximately 2% ment status for the cohort exposed in childhood status (ISEI), coefﬁcient ranged between rainfall) in their year and locationholds of that birth score live 0.12 in standard house- deviationsasset higher index. on No an statistically signiﬁcant relationshipmen for included a matched control group has followed a cohort of Labour supply reduced by 1.7–2.1% per 0.1% excess death Associations with income, occupational status and employ- 0.42% increase in earnings per cm increase in occupational International Socio-Economic Index of Occupational Status Women with 20% higher rainfall (relative to normal local children who were hospitalized for protein-energy malnutrition during the first year of life (matched to a cohort who did not experience the same) in Barbados in 1967– 72.65 Those who experienced the undernutrition episode were found to be lower on social position and standard of early childhood early life years early life early life living indices in adulthood. An early study in India found Height at age 18 that height for age at age 5 years was associated with lower work capacity in the teenage years (14–17).66,67 In the Philippines, length-for-age Z score at age 2 years was found to be associated with an increase in the probability

listing for the military between 1984 and 1997 of being engaged in formal work at age 20–22 for both 1959–61 Famine exposure in 1945–46 Famine exposure in Swedish males en- 1941–42 Famine exposure in 1953–74 Rainfall exposure in men and women.68 Research from US and UK cohort studies have found that height at various stages in childhood and the teenage years is positively related to work status, wages and measures of socioeconomic status in later life.69–73 In a cohort of men born in Helsinki, Finland, between 1934 and 1944, length in the first year of life was associated with subsequent earnings.74 A review of three cohort to event cohort to event effects cohort to event cohort to event Retrospective matching of Retrospective matching of Retrospective matching of cohort studies in low- and middle-income countries found that height-for-age Z score at age 2 was associated with an 8% increase in income in Brazil and Guatemala (although the latter was only significant at the 10% level), and a 21% increase in household assets in India.23 These data are shown in Table 4. Further notes to the studies outlined in Tables 2, 3 and 4 are presented in Table A1 in the Nutrition Survey: CHNS 10% sample Life Survey: IFLS Appendix (available as Supplementary data at IJE online).

Evidence from cross-sectional studies of adult Greece GEIS Census Indonesia Indonesia Family height and adult income A difficulty with interpreting the results in the previous sec-

2014 Sweden Military records Prospective, sibling ﬁxed tion is that it is problematic to compare the magnitude of coefficients across studies because of differences in expos- et al. Natural experiments on the economic consequences of childhood stunting and undernutrition ure and outcome measures. In addition, there are relatively few prospective studies that include measures of childhood Stratmann 2011 Yang 2009 ¨ rges 2013 Germany Census: IPUMS Retrospective matching of Table 3. AuthorsChen and Zhou 2007 China China Health Location and Data Design Year Exposure Result Ju Lundborg Neelsen and Maccini and stunting or undernutrition alongside adult economic 8

Table 4. Prospective studies on the economic consequences of childhood stunting and undernutrition

Authors Location Data Design Year Exposure Result

Galler et al. 2004 Barbados Prospective, 1967–72 Hospitalized for protein-energy Hollingshead social position index (0.62) and matched malnutrition (PEM) during PCA standard of living index (þ0.70) the first year of life Satyanarayana et al. India Prospective 1960–63 Nutritional status age 5 (height Childhood malnutrition was associated with 1978; Satyanarayana for age) physical work capacity et al. 1979 Carba et al. 2009 Philippines Cebu Longitudinal Health Prospective 1983–85 Length-for-age Z-score 40% increase in likelihood of formal work com- and Nutrition Survey pared with not working for men, 0.2 higher likelihood of formal vs informal work for females Barker et al. 2005 Finland Cohort of men born in Prospective Cohort born 1934–44 Height at any age between Each 2-cm increase in length between birth and Helsinki birth and 12 years 1 year was associated with a 3.5% increase in income Case et al. 2005 England National Child Development Prospective Cohort born 1958 Height at age 16 years Increase in employment at age 33 but not at 46, Study: NCDS increase in SES at ages 33 and 46 Case and Paxson 2008 England NCDS Prospective Cohort born 1958 Height at ages 7, 11 and 16 Height associated with income years nentoa ora fEpidemiology of Journal International Montgomery et al. 1996 England NCDS Prospective Cohort Born 1958 Height at age 16 years Odds ratio of 2.41 for being employed (bottom vs top height quintile) Persico et al. 2004 England NCDS Prospective Cohort born 1958 0.88% increase in wages per unit, White male workers only Persico et al. 2004 USA National Longitudinal Survey Prospective Men and women aged Height aged 16–23 years 0.72% increase in wages per unit, White male of Youth: NLSY 1979 14–21 in 1979 workers only Sargent and England NCDS Prospective Cohort born 1958 Height at ages 11, 16, 23 years 0.2% increase in wages for men per cm increase Blanchflower 1994 in height after age 16, 0.1% for women Victora et al. 2008 Brazil Pelotas birth cohort study Prospective Cohort born 1982 Height-for-age score age 2 8% increase in annual income for per SD years increase Victora et al. 2008 Guatemala INCAP Prospective 1969–77 Height-for-age score age 2 Marginally significant (P < 0.1) 8% increase in years annual income per SD increase Victora et al. 2008 India Cohort born in New Deli Prospective 1969–72 Height-for-age score age 2 27% increase in number of household assets 0 No. 0, Vol. 2017, , years nentoa ora fEpidemiology of Journal International Table 5. Quasi-experimental estimates of the association between adult height and wages

Authors Location Data Design Year All Men Women Age N Notes (Association) (Association) (Association) exposure (height) and outcome (wages) measured

Bo¨ ckerman and Finland Older Finnish Twin Twin FE IV 1990–2004 NS 12% Varied 1284 Average yearly earnings over the period; Vainiomaki€ 2013 Cohort Study male estimate is similar but not statistically significant Elu and Price 2013a China CHNS IV 2006 10.30% 5% 7% Varied 1949 Monthly earnings 07 o.0 o 0 No. 0, Vol. 2017, , Elu and Price 2013b Tanzania Tanzanian Household IV 2004 6% 4% Unknown 427 Hourly earnings, height in inches, coeffi- Worker Survey cients are scaled by 0.4, not clear if age is controlled for Gao and Smyth 2010 China China Urban Labour IV 2005 4.80% 10.80% Unknown 11512 Hourly wage; not clear if age is controlled Survey for Heineck 2005 Germany German Socio- IV 2003 NS NS Varied 24000 East Germany; gross monthly earnings; Economic Hausman-Taylor IV Panel:GSOEP Heineck 2005 Germany GSOEP IV 2003 0.50% NS Varied 24000 West Germany; gross monthly earnings Hoddinott et al. 2008 Guatemala INCAP Intervention 2002–04 15.80% NS 25–42 1424 Semi-elasticity estimate is taken from Horton and Steckel (2011) Schultz 2002 Brazil Health and Nutrition IV 1989 8–10% 8–10% 25–54 11855 Survey Schultz 2002 USA NLSY79 IV 1989–93 1–4% 3–6% 20–28 9257 Schultz 2003 Ivory Coast Living Standards IV 1985–89 NS NS Varied 12221 Hourly wage Measurement Surveys: LSMS Schultz 2002; Schultz 2003 Ghana LSMS IV 1985–90 5.60% 7.60% Varied 10888 Hourly wage Thomas and Strauss 1997 Brazil Estudo Nacional da IV 1974–75 1.43% Mean ¼ 36 10675 Hourly wage; men in labour market only; Despesa Familiar: regression included log height, semi- ENDEF elasticity is for a 1-cm increase at mean height Yimer and Fantaw 2011 Ethiopia Ethiopian Urban IV 2001 2% Varied 820 Gross hourly wage; implementation of IV Household Survey: is not clearly defined EUHS

NS, not statistically signiﬁcant. 9 10 International Journal of Epidemiology, 2017, Vol. 0, No. 0 outcomes. An alternative approach to assessing the long- median return for men (based on 20 OLS studies) is 1%, run economic impacts of stunting, which has less data re- and also 1% for women (based on 14 studies). For women, quirements, is to examine the relationship between adult estimates in China, Germany and Australia are found to be height and adult outcomes. The benefits of this approach not statistically significant. are that data on adult height are much more widely avail- For studies that report both IV and linear regression es- able, and it can be implemented with cross-sectional data. timates, Figure 1 demonstrates the difference between the It is also much easier to compare results from this litera- coefficient estimates for these two approaches for men and ture, as there are relatively more studies that examine adult women. Overall, estimates of the median return to height wages or income as the outcome, and a continuous meas- are substantially higher for IV models, particularly for ure of stature as the exposure. As we discuss above, the women (a 5 percentage point point difference). Further dis- wage premium for taller individuals is often used to quan- cussion of these papers is given in the Appendix. A sum- tify the economic impact of childhood growth restriction mary of findings from papers which examine economic because of the association between childhood undernutri- outcomes other than wages is also presented in the appen- 14 tion and adult height. dix (available as Supplementary data at IJE online). Nevertheless, because adult height is an imperfect proxy for our exposure of interest, we therefore separately consider the set of studies that adopt a quasi-experimental in- Cost-benefit analysis of childhood nutrition strumental variables (IV) approach to correct for potential interventions measurement error. Instrumental variables used in this ap- A number of papers conduct cost-benefit analyses of an proach typically include characteristics of respondents’ intervention or package of interventions targeted at reduc- place and time of birth,75 as well as procedures designed to ing childhood stunting or undernutrition, which requires correct for measurement error based on observed charac- costing the economic impact. The approach typically teristics only,76 and finally, twin differences in height and adopted in these studies can be summarized as follows. body mass kndex (BMI).77 We provide a methodological First, the treatment effect of the programme in terms of the discussion of the different approaches in the Appendix expected reduction in the exposure (for example, the prob- (available as Supplementary data at IJE online). These IV ability of being stunted) is calculated. Then, the treatment results are presented in Table 5, where we report estimates effect is multiplied by the number of affected children to of the expected change in wages (measured in percent) obtain an estimate of the reduction in stunting prevalence associated with a 1-cm change in adult height (known in induced by the treatment. The economic benefits of this re- the economics literature as the semi-elasticity). duction are then usually calculated by calibrating the re- For men, coefficient estimates range from 1% to turns to height using the existing literature. For example, if þ10%, with no statistically significant association found the intervention increased average height by 1 cm among in Finland, East Germany and Ivory Coast.75–85 For 100 children, and the estimated return to height is calcu- women, coefficient estimates range from 4% in Tanzania lated at 3%, the programme is valued at 1*100*3%*aver- and Ivory Coast to þ12% in Finland, with non-significant age wages, potentially with some correction for estimates observed in Germany and Ivory Coast. The discounting and estimates of labour supply across the life Tanzanian and Ivory Coast estimates for women are not- course. Additional benefits can be included, for example able outliers as they are negative. One study gave results the return to improvements in test scores,5 or reductions in for a combined sample (a 2% return in Ethiopia). Mean direct costs such as lower treatment costs for illness associ- rates of return associated with an additional centimetre of ated with improvements in health status. Some studies also height are 5% for men in 12 studies and 6% for women in include the value of lives saved as a result of these 11 studies. Assuming non-significant estimates are equal to interventions. zero lowers the mean return to 3% for men but does not Using this approach, a micronutrient supplementation affect the estimate for women. Median rates of return to a and early childhood stimulation programme in Nicaragua centimetre of height are 4% for men and 6% for women. was found to have a cost-benefit ratio of 1.5. Benefits for Corresponding linear regression estimates from studies programme participants were calibrated using estimates that only implement ordinary least squares (OLS) models from the literature on the returns to test scores which were are presented in Table 6.13,58,70,72,73,79,82,86–97 Using this estimated to be affected by the programme.98 In an ana- approach, coefficient estimates are almost all less than a lysis of a stunting intervention in Indonesia, the pro- percentage point. Exceptions are men in one study in gramme was found to have a cost-benefit ratio of 2.08 on China (3%), men and women in Indonesia (8% and 13%, the basis of productivity enhancements from reduced respectively) and men in Mexico (2%). Here the mean and undernutrition, earnings from deaths averted, and Table 6. Linear regression estimates of the association between adult height and wages nentoa ora fEpidemiology of Journal International

Authors Location Data Design Year All Men Women Age N Notes (Association) (Association) (Association) exposure (height) and outcome (wages) measured

Bockerman et al. 2010 Finland Health 2000 in Finland OLS 2000–01 0.67% 0.40% Mean ¼ 44 2506 Hourly earnings, which the authors calculate as annual wage divided first by 52, and then by the individual’s self-reported number of weekly working hours. Case and Paxson 2008; England NCDS OLS 1991 0.65% 0.43% 33 5833 Average hourly earnings; height was meas- 07 o.0 o 0 No. 0, Vol. 2017, , Case and Paxson 2010 ured in inches, coefficient is scaled by 0.4 Case and Paxson 2008; England NCDS OLS 2000 0.63% 0.50% 42 5833 Average hourly earnings; height was meas- Case and Paxson 2010 ured in inches, coefficient is scaled by 0.4 Case and Paxson 2010 England British Cohort Study: BCS OLS 2000 0.30% 0.28% 30 5424 Average hourly earnings; height was measured in inches, coefficient is scaled by 0.4 Case and Paxson 2010 USA Panel Study of Income OLS 1988–97 0.38% 0.18% 25–55 31996 Average hourly earnings; height was meas- Dynamics: PSID ured in inches, coefficient is scaled by 0.4 Case and Paxson 2010 USA Health and Retirement OLS 1992–2004 0.70% 0.68% 55–74 27606 Average hourly earnings; height was meas- Study: HRS ured in inches, coefficient is scaled by 0.4 Case et al. 2009 England British Household Panel OLS 1997–2005 0.40% 0.20% 21–60 42666 Average hourly earnings; height was meas- Survey: BHPS ured in inches, coefficient is scaled by 0.4 Haddad and Bouis 1991 Philippines OLS 1984–85 0.7% – Varied 390 Real daily wage, rural agricultural work; 0.8% Hausman-Taylor IV applied to variables other than height Heineck 2008 England BHPS OLS 2004 0.60% 1.40% 21–50 4650 Results without education Hu¨ bler 2009 Germany GSOEP OLS 1985–2004 0.25% NS 22–55 36754 Association was found to be non-linear Kortt and Leight 2010 Australia Household, Income and OLS 2006–07 0.22% 0.28% NS 25–54 6822 Hourly wages Labour Dynamics in Australia: HILDA Lindqvist 2012 Sweden Longitudinal INdividual OLS 2006 0.33% Varied 13414 Annual wages; men born between 1965 and DAta for Sweden: 1974 LINDA Lundborg et al. 2014 Sweden Swedish males enlisting Sibling FE 2003 0.42% 28–32 450000 Annual earnings; height measured at 18 for the military between years; height associations are non-linear 1984 and 1997 Persico et al. 2004 USA NLSY79 OLS 1996 0.70% 35 1577 Annual income; height was measured in inches, coefficient is scaled by 0.4 Persico et al. 2004 England NCDS OLS 1991 0.88% 33 1772 Income period varies; height was measured in inches, coefficient is scaled by 0.4 11 (continued) 12 International Journal of Epidemiology, 2017, Vol. 0, No. 0

household savings from diarrhoea costs avoided.6 In a review of cost-benefit ratios of nutrition interventions, estimates ranged from 3.5:1 to 42.7:1 per child, with a median of 17.9:1.22,99 A similar methodology has been used to estimate the aggregate burden of stunting worldwide. Instead of considering a particular intervention, these studies calculate the cost savings associated with reducing stunting prevalence to zero in a country. Then, wage returns for each stunted child, under the hypothetical scenario that every currently stunted child was no longer stunted, are aggregated. An

full time labour market early example of a study which attempts to quantify the Notes national costs associated with stunting is that of Ross et al.

N (2003), who examine the impact of undernutrition on eco- 1179 nomic productivity in China.100 Using estimates of the impact of stunting on productivity from the literature, they

þ conclude that productivity gains due to reductions in child

Age exposure (height) and outcome (wages) measured stunting over the period 1991 to 2001 were worth US$12 billion (Yuan 101 billion) in 2001. Conducting a similar analysis, Alcazar et al. (2012) found that productivity- related costs of stunting in Peru were also large [2.2% of Women (Association) gross domestic product (GDP)].101 Bagriansky et al. (2014) estimated the impact of undernutrition at more than US$400 million annually in Cambodia, or approximately Men

(Association) 2.5% of yearly GDP, of which 57% is a result of children being affected.102 A similar approach involves aggregating the costs accru- ing to the population in a country as a whole. For example,

(Association) add up the direct costs for affected individuals in a country, potentially using different methodologies as a sensitivity analysis, then divide by the total population in that country

2006 0.14%to obtain an Varied estimate 2510 Women only; adjusted for selection into the of per capita costs, which could be expressed as a percentage of GDP. Horton and Ross (2003) estimate the productivity costs of anaemia at Heckman 0.57% of GDP in 10 countries,103 and Horton and Steckel OLS 2012OLS, OLS 2.60% 2002, 2005 NS 45 2.30% 25–65 3860 Men only; hourly earnings (2011) calculate the global economic losses associated with malnutrition by aggregating losses for individual countries.31 Assuming that the impact of height on productivity is captured by the association of height with wages (earnings), and that this translates into economic growth via the share of wages in national income (approximately 50%), of Aging: CHARLS Postsecondary Education Database: TIPED Survey: MxFLS they consider the differential return to height at different levels of mean height based on linear regression and estimates from the literature. At the country level, they obtain estimates of the wage return to 1 cm increase in height of England NCDS OLS 1981 0.20% 0.10% 23 12537 Height at age 16; hourly earnings 4.5% at 170 cm, 4% at 171 cm, 3.5% at 172 cm and 0.5% at 178 cm. Aggregating wage impacts, these assumed prod-

2015 Germany GSOEP OLS 2002–12 0.40% 0.50%uctivity 0.30% losses Varied 92248 are Hourly earnings combined with data on average height to

2012 China China Longitudinal Study give estimated costs as a percentage of national income in et al. . Continued each country. Results imply that the annual GDP loss due et al. to undernutrition is up to 12% in low- and middle-income NS, not statistically signiﬁcant. Blanchﬂower 1994 Table 6 Authors Location Data Design Year All Sargent and Smith Rietveld Sohn 2014Tao 2014 Indonesia IFLSVogl 2014 Taiwan Taiwan Integrated countries. Mexico Mexican Family Life OLS Globally, 2015 these losses 7.50% are 13% estimated 20–65 9306 to Annual earnings have International Journal of Epidemiology, 2017, Vol. 0, No. 0 13 10 8 6 4 2 Median Return to 1 CM Increase in Height 0 Men IV Men OLS Women IV Women OLS

Figure 1. Comparison of median estimates of the wage return to a 1-cm increase in height from instrumental variables (IV) and linear regression (OLS). Error bars show the interquartile range. fallen from 12% of world GDP in 1900 to 6% in 2000. The corresponding projections for 2050 imply that losses will be of the order of 6%. Based on a model originally de- veloped for Latin America,104 the Cost of Hunger in Africa

(COHA) study [http://www.costofhungerafrica.com] aims Figure 2. Summary of the pathways linking stunting to economic to provide economic estimates of the costs of hunger in 13 growth. 106 countries. A recent report on Malawi from this study Adapted from Bloom et al. (2014). group indicates that the costs associated with stunting 105 spillover effects of stunting on economic growth. The po- were of the order of 10% of GDP per year. Overall, there is therefore a multitude of evidence that tential for these effects can be informed by considering the nutrition interventions are highly cost effective, and that standard approach in macroeconomic growth models the economic burden of undernutrition on society as a where national income is defined as a function of labour, whole is likely to be large; however, these studies crucially capital and the efficiency with which labour and capital in- 108 rely on estimates of the economic return to factors such as puts are combined (or technological progress). From this adult height or reductions in child stunting. In practice, perspective, the pathways through which undernutrition there does not seem to be a consensus in the literature as to could affect aggregate economic growth include increases what return to height should be used. In addition, studies in morbidity, mortality and health expenditure and subse- that aggregate from individual losses may be underesti- quent reductions in human capital investment (for example, mates of the total economic impact because they do not education), physical capital investment and labour supply. account for spillover effects on economic growth.106 Reductions in productivity because of ill health or work capacity for any given labour supply, and reductions in human capital and technological progress (due to lower lev- The impact of stunting on economic growth els of educational attainment and infrastructure) are likely Results in the previous section reflect the potential impact to negatively impact not only on individuals themselves, of individual undernutrition on individual economic out- but also on economic growth when a substantial proportion comes. The pathways linking stunting to individual income of a country’s population are affected by stunting. Other have been discussed previously.15–17,22,35 However, relevant pathways include the impact of undernutrition on individual-level estimates do not take account of effects on chronic disease, which would involve the diversion of pro- aggregate capital formation, labour markets, savings behav- ductive savings (which boost investment) towards treat- iour, investment behaviour and other factors which make ment costs.106 These pathways are summarized in Figure 2. up the determinants of aggregate output. Estimating the full There is a literature in economics which examines costs of undernutrition to society requires accounting for whether there is an effect of health on economic growth. all of these potential effects. However, whereas height and However, there are relatively few studies that consider wages tend to be correlated at the aggregate level,107 in the undernutrition specifically (either childhood undernutrition literature there has been surprisingly little attention paid to or adult undernutrition) as an input in these production 14 International Journal of Epidemiology, 2017, Vol. 0, No. 0 function models of the aggregate economy. Some recent ex- relative terms (the association in percent). Once estimates ceptions are Chakraborty et al. (2010), Dalgaard and are rescaled, the magnitudes of the reported coefficients Strulik (2015) and Piper (2014).109–111 Estimating this rela- appear similar.119 Across six studies, the impact of a 10% tionship in practice with currently available data is problem- increase in GDP per capita was found to be in the range of atic because it is difficult to assess whether the causal a 0-2% reduction in stunting.119–125 For example, pathway runs from nutrition to economic growth, or from Harttgan et al. (2013) find that although levels of GDP per economic growth to nutrition. Most likely the relationship capita have increased substantially in many low- and is bidirectional, but this makes it difficult to interpret par- middle-income countries over recent decades, levels of ameter estimates from models that do not account for this stunting and undernutrition showed very little improve- reverse causality, because estimates of the impact on growth ment.124 In this study, a 10% increase in GDP per capita likely also incorporate some of the effect in the opposite dir- was associated with a 1.5–1.7% reduction in stunting, ection, and vice versa. Recent summaries of the general lit- which is similar to estimates of approximately 2% ob- erature on health at the macro and micro levels are tained in Heltberg (2009).122 Ruel et al. (2013) reported provided elsewhere.112–114 There is a small number of stud- that a 10% increase in GDP per capita was associated with ies that examine the relationship between adult stature spe- a reduction in stunting prevalence of around 6 percentage cifically and economic growth. Weil (2007) incorporates points.123 However, their study focused on the long-run height alongside other health measures into an augmented impacts, as opposed to the other papers which considered production function, and finds that health differences more short-term associations with GDP. worldwide account for a relatively small proportion of dif- There are a number of additional studies, most of which ferences in GDP (around 10% of the variance in log GDP report similar results to the above. Smith and Haddad per worker).115 Adopting an empirical approach with a co- (2015) estimate that a 10% increase in GDP per capita is integrating model to account for reverse causality, Arora associated with a 1.7% reduction in stunting.1 Their esti- examines whether changes in health, including adult stature, mates of the long-run impact of GDP per capita are larger, contributed to growth among a group of 10 industrialized at around 6%, and comparable to their earlier estimates in countries over the course of the past century, and finds that Smith and Haddad (2002) and Haddad et al. (2003),126,127 health contributed between 30% and 40% to the economic where increases in national income over the 25-year period growth rates over this period.116 Also in a co-integration from 1970 to 1995 were found to have led to roughly half analysis, Marıa-Dolores and Martınez-Carrion find a bidir- of the total reduction in the developing-country prevalence ectional relationship between height and economic growth of child undernutrition over the period. In contrast, a re- among Spanish regions in the period 1850–1958.117 The cent analysis which adopted a multilevel approach in evidence demonstrates a strong association between eco- Indian states, found that economic growth was not associ- nomic growth and health, but because of the difficulties ated with reductions in stunting or other measures of associated with testing theoretical models of how economic undernutrition.128 As far as we are aware, only one paper growth is produced, it is currently difficult to quantify the has examined whether the timing of economic growth is magnitude of these effects. However, one recent example of important for height, and found that economic growth in a paper uses an instrumental variables approach in an effort puberty and in the first year of life were most associated to overcome the problems associated with reverse causality, with the adult height of women in sub-Saharan Africa.129 and finds that each centimeter increase in average popula- Although the magnitude of the relationship between tion height is expected to raise income per capita by 6%.118 GDP per capita and stunting continues to be This estimate would imply that the magnitude of the return debated,130,131 there appears to be some agreement that to increases in height at the national level is substantial. economic growth alone is unlikely to be able to achieve substantial reductions in the prevalence of stunting, and that any effects are too small to rely on national income The impact of economic growth on stunting alone for achieving large reductions in child undernutri- Some papers in the literature have found that economic tion, at least in the short run.1 The fact that some coun- growth is associated with a reduction in the prevalence of tries, such as Sri Lanka, or regions within countries, such child stunting, but the magnitude of the relationship has as Kerala in India, have lower prevalence of stunting than generally been found to be small. Interpretation of esti- their incomes would suggest places emphasis on other fac- mates can be complicated by the fact that some studies re- tors such as the local policy environment and the role of port the impact of GDP per capita on stunting prevalence public health nutrition programmes. A recent paper sug- in absolute terms (the association in percentage points), gests that differences in stunting prevalence across Indian whereas others report the impact on stunting prevalence in states is less due to differences in inputs and more likely International Journal of Epidemiology, 2017, Vol. 0, No. 0 15 due to differences in the predictive power of these inputs that outcome measures are different (for example, hourly for undernutrition.132 Moreover, a series of countries have wages versus income), different methodologies are em- been able to achieve rapid improvements in child nutri- ployed and different control variables are used across the tional status.121 Recent reports from the United Nations studies. Age and period effects are also likely to be import- Children’s Fund (UNICEF) and the International Food ant but are not always accounted for. A methodological Policy Research Institute contain a series of case studies on drawback of almost all the studies we reviewed is that very successful reductions in stunting prevalence in the best per- few adjust for the decision on whether to participate in the forming countries.38,133,134 labour market, and only consider the earnings of those Therefore, it seems that other more direct interventions who are employed. It could be that those who are not cur- will be required to achieve global targets for reductions in rently employed would have lower earnings if they entered stunting and undernutrition among children. The literature the labour market, and those outside the labour market has begun to emphasize that the quality of economic may also be the most likely to be of lower height. An ex- 84 growth is likely to be important for how income gains ception is a study of female graduates in Taiwan. From translate into reductions in child undernutrition.135 The that perspective, the results presented here may be under- impact of intermediary factors on stunting, such as sanita- estimates. The studies we report on also use a variety of tion, governance, the roll-out of nutrition programmes, different exposures to measure the impact of child under- growth in food production and infrastructure, access to nutrition, and it is important to bear in mind that the re- health services and infrastructure, governance, education sults are therefore not always directly comparable. and fertility have all been investigated previ- Intervention and prospective analyses tend to rely on meas- ously.1,121,125,136,137 Focusing on promoting economic uring childhood undernutrition using height-for-age, growth that raises the income of the least well off, and im- which is understandable given that this approach provides proves the quality and equity of these intermediary inputs, objectively measured information which is feasible to col- is thus likely to be the most effective way of ensuring that lect in a variety of contexts, including household surveys. economic growth leads to reductions in the prevalence of Whereas stunting can be used to identify growth and nutri- child stunting.138 tional deficiencies, along with cumulative undernutrition, these measures also have their disadvantages (for example, they may capture other aspects of early life conditions Discussion including disease environment and genetic growth potential, and have a lesser capacity to capture marginally inad- Summary of the evidence linking childhood equate diets or short-run episodes).12 Cross-sectional stunting and undernutrition to economic analyses rely on proxying childhood nutritional status with outcomes adult height, which also has its limitations. It is difficult to The evidence reviewed in this paper supports the hypoth- assess the extent to which these issues affect our conclu- esis that children affected by stunting or undernutrition are sions, without further data from prospective studies which negatively affected in terms of a variety of economic out- credibly address measurement error, unobserved con- comes, including productivity, occupational status and founding, and selection into the labour market. An assess- wages. The magnitude of the relationship between stunting ment of publication bias in the literature would also be and wages is larger in intervention studies (two nutrition beneficial. It is important to bear in mind that we do not programmes were associated with a 25% and a 46% in- have the same kind of evidence that would be provided by crease in adult wages for affected children, respectively) multiple RCTs conducted in a variety of different contexts, than quasi-experimental studies (where we find that each and therefore we have tried to summarize the weight of the centimetre increase in adult height is associated with an in- available evidence across a range of studies from different crease in wages of 4% for men and 6% for women), which methodologies and of varying quality. One question is how is in turn larger than that found in observational data to reconcile that results from the two experimental studies (where the corresponding wage estimate is 1% for men are substantially higher than median quasi-experimental and women). estimates. It is likely that there are at least two pathways A theme in this review is that there is a great deal of het- linking stunting to adult outcomes, including a pure stature erogeneity in terms of coefficient estimates, across both effect, and the effect of lost growth potential encompassing countries and genders, although estimates in low- and cognitive impacts of undernutrition. Unlike most quasi- middle-income countries do appear larger on average than experimental studies, long-run follow up of nutrition inter- those from high-income countries such as the UK and the ventions can isolate the latter, which we would expect to USA. This heterogeneity is likely to partly reflect the fact be larger. It remains to be seen whether the magnitude 16 International Journal of Epidemiology, 2017, Vol. 0, No. 0 found in the two existing studies is observed in subsequent short run. A focus on the quality of economic growth, trials, but nevertheless, even if we focus solely on the lower intermediary inputs including sanitation, education, qual- quasi-experimental median estimates, the evidence from ity of diets and access to basic health services,143 and a different sources is still generally consistent with the combination of poverty reduction and direct nutrition hypothesis of substantial economic returns to nutrition in interventions, are likely to be most effective at achieving early childhood. large reductions in stunting.127 Stature in adulthood is also linked to other economic outcomes, including occupational status, and other meas- Implications for countries with high stunting ures of socioeconomic position. Studies which examine po- prevalence in the context of Sustainable tential mechanisms indicate that there is a direct Development Goals post 2015 association of stature with productivity and fatigue.139,140 An alternative set of studies which examine more short-run There has been some progress in reducing child stunting relationships find that child undernutrition affects cogni- and undernutrition over recent decades, with stunting tion and schooling. Controlling for these variables in prevalence falling from 50% in 1970 to 30% in 2010 height regressions generally attenuates coefficient esti- among low- and middle-income countries. However, mates, supporting this interpretation, at least in low- and stunting remains high in some regions, and is currently at middle-income countries. Health effects of stunting across 38% in South Asia and 37% in sub-Saharan Africa. The the life cycle are also likely to be substantial, as are effects current momentum and international agreement on the of in utero environment on health and economic outcomes. importance of reducing undernutrition among children Separating out optimal timing of investments in infants are apparent in the inclusion of food security and nutri- and children remains an important direction for future re- tion as one of the Sustainable Development Goals, the search.141 Intergenerational transmission of disadvantage emergence of initiatives such as the Scaling Up Nutrition is another pathway which we did not cover in this review (SUN) movement [http://scalingupnutrition.org/] and the except insofar as it relates to economic outcomes, but this targets for reductions in stunting set by the World Health is also likely to be an important consequence of child Assembly and United Nations and endorsed by the undernutrition.19,142 Sustainable Development Goals (SDGs).38 However, fur- Cost-benefit analyses that evaluate programmes imple- ther evidence is needed to inform how best to prioritize menting nutrition interventions tend to find that they are effective and cost-effective interventions to reduce stunt- cost-beneficial, some very cost-beneficial, and studies ing in the most adversely affected areas. Reviews of ef- which aggregate costs across all affected individuals in a fective treatments for the direct causes of growth country or set of countries find that the total costs of child restriction have identified promising interventions, includ- stunting and undernutrition are high. Our median quasi- ing: periconceptual folic acid supplementation; maternal experimental estimate of the return to 1 cm of height of energy, protein, calcium and micronutrient supplementa- 4% for men is similar to that used in previous cost-benefit tion; promotion of breastfeeding and appropriate comple- analysis of 7%,6 research on economic growth of 3.5%115 mentary feeding of children; vitamin A and zinc and global estimates of the economic burden of stunting of supplementation for children; and management of acute 0.5% to 4.5% (depending on the country).31 When a high malnutrition.41 However, to unleash the potential of nu- proportion of a cohort within a country are affected, these trition programmes, progress is needed in addressing per- studies may miss spillover effects on labour markets and sistent socioeconomic inequities.2 Intervention studies technological progress and their consequent impact on eco- suggest that a combination of nutrition and stimulation nomic growth. This is an important direction for future re- packages in early childhood may have the greatest search, and taking account of externalities in the impact.27,50,144 interaction between undernourished individuals, cohorts Although economic growth in South Asia has been and labour markets on economic growth, potentially using rapid, with more than a doubling of GDP over the past a production function approach such as that taken in more four decades, levels of per capita GDP remain low. India general studies of health and GDP,106 would be of great experienced 8% growth in GDP from 2000 to 2010, and interest. In contrast to the impact of stunting or undernu- during the period 1981–2005 India’s poverty rate fell from trition on economic growth, there are relatively more stud- 60% to 42%.4 Despite this being similar to China’s reduc- ies that examine the impact of economic growth on tions in poverty, stunting fell much more rapidly in China stunting. In this literature, even the studies that do find an than in India over the period. One potential explanation association between economic growth and stunting agree for this is the low coverage of nutrition interventions. For that the magnitudes involved are not large, at least in the example, only 25% of vulnerable children benefited from International Journal of Epidemiology, 2017, Vol. 0, No. 0 17 feeding interventions and only 30–40% received vitamin A interventions identified in the literature and promoted supplements.4 Uneven economic growth which does not internationally. achieve gains spread equally across the distribution of At the national level, progress has been uneven at reduc- households is another potential explanation for the lack of ing stunting, and South Asia and sub-Saharan Africa in improvements observed in India following rising aggregate particular have lagged behind other regions. In India, the income per capita.138,145 slow improvement in reducing child undernutrition stands In a recent assessment of the underlying determinants out because of rapid economic growth. Focusing on com- of stunting in South Asia, Smith and Haddad (2015) binations of nutrition programmes and proximal determin- point to factors other than economic growth which are ants, such as gender equality and sanitation, may provide a likely to be relevant for improving levels of child under- more reliable method of reducing child undernutrition nutrition. Access to sanitation, dietary diversity of food than low quality growth that is not broad-based and bene- supplies and gender equality have potentially high rates ficial for poorer or more vulnerable children and house- of return because they are farthest below their desired holds. Because of likely spillover effects of reductions in levels. In particular, only 38% in South Asia have ad- stunting prevalence on labour markets and productivity, equate sanitation access and only 40% of the food supply investments targeted at reducing child stunting and under- is made up of non-staples, resulting in poor diet quality nutrition are likely to have substantial returns to society in as highlighted by the fact that fewer than 25% of young terms of increases in economic growth and human capital children are fed diets that meet the minimum adequacy formation. for child growth and development.1,135 Another area of emphasis is governance and accountability, particularly given that children are especially vulnerable to poor pub- Supplementary Data lic services, but are not easily heard because of their lack Supplementary data are available at IJE online. of political voice and the relative lack of attention paid to undernutrition.4 Interventions targeting these factors are largely in the Funding hands of states and provinces in countries such as India Financial support for this analysis was provided by UNICEF and Pakistan, respectively. Coupled with the results pro- Regional Office for South Asia. vided in this paper and the literature, there is therefore the Conflict of interest: None to declare. The opinions expressed in this opportunity to view investments in child nutrition as a paper are those of the authors and do not necessarily reflect an offi- strategy for economic growth and human capital forma- cial position of the institutions that they are affiliated with. tion at the state and local levels. States in India and provinces in Pakistan have gained increasing autonomy for Acknowledgments administering major family and child programmes over the We are grateful to Matthias Blum, John Hoddonitt, and seminar past three decades, with decentralization/devolution of nu- participants at the 2016 Workshop on Economics and Human Biology for comments and suggestions. trition and other social welfare budgets.146 References

Conclusions 1. Smith LC, Haddad L. Reducing child undernutrition: past drivers and priorities for the post-MDG era. World Dev In a review of evidence assessing the economic impacts of 2015;68:180–204. childhood stunting and undernutrition, we find that results 2. Oruamab RS. Child malnutrition and the Millennium from intervention studies and quasi-experimental research Development Goals: much haste but less speed?. Arch Dis consistently indicate substantial economic returns to linear Child 2015;100:S19–22. growth and reductions in stunting at the individual level. 3. Stevens GA, Finucane MM, Paciorek CJ, et al. Trends in mild, The median return in instrumental variables analyses to a moderate, and severe stunting and underweight, and progress 1-cm increase in height was found to be 4% for men and towards MDG 1 in 141 developing countries: a systematic ana- 6% for women. Two long-term follow-ups of intervention lysis of population representative data. Lancet studies show even more substantial returns to nutrition- 2012;380:824–34. 4. Haddad L. Why India needs a national nutrition strategy. BMJ related programmes (16% per centimetre in a study in 2011;343:d6687. Guatemala). On the basis of these estimates, nutrition in- 5. Fink G, Peet E, Danaei G, et al. Schooling and wage income vestments are likely to be cost beneficial, especially if they losses due to early-childhood growth faltering in developing focus on the 1000 days from conception to age 2 years and countries: national, regional, and global estimates. Am J Clin on adolescence, and they prioritize evidence-based Nutr 2016;104:104–12. 18 International Journal of Epidemiology, 2017, Vol. 0, No. 0

6. Qureshy LF, Alderman H, Rokx C, Pinto R, Wai-Poi M, 25. Alderman H, Sahn DE. Public and Private Returns to Investing Tandon A. Positive returns: cost-beneﬁt analysis of a stunting in Nutrition. Komlos J, Kelly IR (eds). Oxford Handbook of intervention in Indonesia. J Dev Eff 2013;5:447–65. Economics and Human Biology. Oxford, UK: Oxford 7. Currie J. Inequality at Birth: Some Causes and Consequences. University Press, 2016. Am Econ Rev 2011;101:1–22. 26. Martorell R. The policy and program implications of research on 8. Almond D, Currie J. Killing Me Softly: The Fetal Origins the long-term consequences of early childhood nutrition: lessons Hypothesis. J Econ Perspect 2011;25:153–72. from the INCAP follow-up study. In: Freire W (ed.). Nutrition 9. Currie J, Vogl,T. Early-Life Health and Adult Circumstance in and an Active Life: From Knowledge to Action. Washington Developing Countries. Annu Rev Econ 2013;5:1–36. D.C.: Pan-American Health Organization; 2005. 10. Delaney L, Smith JP. Childhood Health: Trends and 27. Alderman H, Behrman JR, Grantham-McGregor S, Lopez-Boo Consequences over the Life-course. Future Child F, Urzua S. Economic perspectives on integrating early child 2012;22:43. stimulation with nutritional interventions. Ann N Y Acad Sci 11. Almond D, Currie J. Human Capital Development before Age 2014;1308:129–38. Five. In: Ashenfelter O, Card D (eds). Handbook of Labor 28. Strauss J, Thomas D. Health, nutrition, and economic develop- Economics. Volume 4, Part B. New York, NY: Elsevier, 2011. ment. J Econ Lit 1998;36:766–817. 12. Corsi DJ, Subramanyam MA, Subramanian S. Commentary: 29. Fogel R. Economic Growth, Population Theory, and Measuring nutritional status of children. Int J Epidemiol Physiology: The Bearing of Long-Term Processes on the 2011;40:1030–36. Making of Economic Policy. Am Eco. Re 1994;84:369–95. 13. Case A, Paxson C, Islam M. Making sense of the labor market 30. Halim N, Spielman K,Larson B. The economic consequences of height premium: Evidence from the British Household Panel selected maternal and early childhood nutrition interventions in Survey. Econ Lett 2009;102:174–76. low-and middle-income countries: a review of the literature, 14. Stein AD, Wang M, Martorell R, et al. Growth Patterns in 2000—2013. BMC Women’s Health 2015;15:33. Early Childhood and Final Attained Stature: Data from Five 31. Horton S, Steckel RH. Malnutrition: Global Economic Losses Birth Cohorts from Low- And Middle-Income Countries. Am J Attributable to Malnutrition 1900–2000 and Projections to Hum Bio 2010;22:353–59. 2050. Copenhagen: Copenhagen Consensus Center, 2011. 15. Alderman H. The economic cost of a poor start to life. J Dev 32. Steckel RH. Stature and the Standard of Living. J Econ Lit Orig Health Dis 2010;1:19–25. 1995;1903–40. 16. Alderman H. Economic drivers and consequences of stunt- 33. Steckel RH. Biological measures of economic history. Annu ing. In: Gillman MW, Gluckman PD, Rosenfeld RG (eds). Rev Econ 2013;5(1):401–23. Recent Advances in Growth Research: Nutritional, 34. Steckel RH. Heights and human welfare: Recent developments Molecular and Endocrine Perspectives.Basel,Switzerland: and new . Econ Hist 2009;46:1–23. Karger, 2013. 35. Hu¨ bler O. Height and Wages. In: Komlos J, Kelly IR (eds). The 17. Behrman JR, Bhalotra S, Deolalikar AB, Laxminarayan R, Oxford Handbook of Economics and Human Biology. Nandi A. Capital and Productivity Beneﬁts of Early Childhood Oxford, UK: Oxford University Press, 2016. Nutritional Interventions. In: Jamison D, Gelband H, Horton 36. Schultz TP. Human capital, schooling and health. Econ Hum S, Jha P, Laxminarayan R, Nugent R. (eds). Disease Control Bio 2003;1:207–21. Priorities, 3rd edition. Volume 8. Washington D.C.: World 37. Sudfeld CR, McCoy DC, Danaei G, et al. Linear Growth and Bank; 2017. Child Development in Low-and Middle-Income Countries: A 18. Behrman JR. The economic rationale for investing in nutrition Meta-Analysis. Pediatrics 2015;135:e1266–75. in developing countries. World Dev 1993;21:1749–71. 38. UNICEF. Improving Child Nutrition: The Achievable 19. Behrman JR. Early life nutrition and subsequent education, Imperative for Global Progress. New York, NY: United health, wage, and intergenerational effects. In: Spence M, Nations Children’s Fund, 2013. Lewis M. editors. Health and Growth. Washington D.C.: 39. World Bank. Independent Evaluation Group International World Bank, 2009. Bank for Reconstruction and Development. What Can We 20. Dewey KG, Begum K. Long-term consequences of stunting in Learn From Nutrition Impact Evaluations?: Lessons From a early life. Matern Child Nutr 2011;7:5–18. Review of Interventions to Reduce Child Malnutrition in 21. World Bank. From Early Child Development to Human Developing Countries. New York, NY: World Bank, 2010. Development: Investing in Our Children’s Future. Young ME 40. Bhutta ZA, Ahmed T, Black RE, et al. What works? (ed.). New York, NY: World Bank, 2002. Interventions for maternal and child undernutrition and sur- 22. Hoddinott J, Alderman H, Behrman JR, Haddad L, Horton S. vival. Lancet 2008;371:417–40. The economic rationale for investing in stunting reduction. 41. Bhutta ZA, Das JK, Rizvi A, et al. Evidence-based interventions Matern Child Nutr 2013;9:69–82. for improvement of maternal and child nutrition: what can be 23. Victora CG, Adair L, Fall C, et al. Maternal and child undernu- done and at what cost?. Lancet 2013;382:452–77. trition: consequences for adult health and human capital. 42. World Bank. Repositioning Nutrition as Central to Lancet 2008;371:340–57. Development: A Strategy for Large Scale Action. New York, 24. World Bank. Early child development from measurement to NY: World Bank Publications, 2006. action: a priority for growth and equity. Young ME, 43. Hoddinott J, Maluccio JA, Behrman JR, Flores R, Martorell R. Richardson LM (eds.). Washington DC: World Bank, 2007. Effect of a nutrition intervention during early childhood on International Journal of Epidemiology, 2017, Vol. 0, No. 0 19

economic productivity in Guatemalan adults. Lancet 63. Victora CG, Barros FC. Cohort Profile: The 1982 Pelotas 2008;371(9610):411–16. (Brazil) birth cohort study. Int J Epidemiol 2006;35:237–42. 44. Stein AD, Melgar P, Hoddinott J, Martorell R. Cohort profile: 64. Power C, Elliott J. Cohort Profile: The 1958 British birth cohort The Institute of Nutrition of Central America and Panama (national child development study). Int J Epidemiol (INCAP) nutrition trial cohort study. Int J Epidemiol 2006;35:34–41. 2008;37:716–20. 65. Galler JR, Bryce C, Waber DP, Zichlin ML, Fitzmaurice GM, 45. Haas JD, Murdoch S, Rivera J, Martorell R. Early nutrition Eaglesfield D. Socioeconomic outcomes in adults malnourished and later physical work capacity. Nutr Rev 1996;54:S41–48. in the first year of life: a 40-year study. Pediatrics 46. Haas JD, Martinez EJ, Murdoch S, Conlisk E. Nutritional sup- 2012;130:e1–7. plementation during the preschool years and physical work 66. Satyanarayana K, Nadamuni NA, Narasinga RB. Nutrition, capacity in adolescent and young adult Guatemalans. Nut physical work capacity and work output. Indian J Med Res 1995;125(Suppl 4): 1078S. 1978;68:88–93. 47. Hoddinott J, Behrman JR, Martorell R. Labor force activities 67. Satyanarayana K, Naidu AN, Rao BN. Nutritional deprivation and income among young Guatemalan adults. Food Nutr Bull in childhood and the body size, activity, and physical work cap- 2005;26:98S–109. acity of young boys. Am J Clin Nutr 1979;32:1769–75. 48. Martorell R, Melgar P, Maluccio JA, Stein AD, Rivera JA. The 68. Carba DB, Tan VL, Adair LS. Early childhood length-for-age is nutrition intervention improved adult human capital and eco- associated with the work status of Filipino young adults. Econ nomic productivity. J Nutr 2010;140:411–14. Hum Biol 2009;7:7–17. 49. Hoddinott J, Behrman JR, Maluccio JA, et al. Adult conse- 69. Case A, Fertig A, Paxson C. The lasting impact of childhood quences of growth failure in early childhood. Am J Clin Nutr health and circumstance. J Health Econ 2005;24:365–89. 2013;98:1170–78. 70. Case A, Paxson C. Stature and Status: Height, Ability, and 50. Gertler P, Heckman J, Pinto R, et al. Labor market returns to Labor Market Outcomes. J Polit Econ 2008;116:499–532. an early childhood stimulation intervention in Jamaica. Science 71. Montgomery SM, Bartley MJ, Cook DG, Wadsworth ME. 2014;344:998–1001. Health and social precursors of unemployment in young men in 51. Chen Y, Zhou L-A. The long-term health and economic conse- Great Britain. J Epidemiol Community Health 1996;50:415–22. quences of the 1959–1961 famine in China. J Health Econ 72. Persico N, Postlewaite A, Silverman D. The Effect of 2007;26:659–81. Adolescent Experience on Labor Market Outcomes: The Case 52. Neelsen S, Stratmann T. Effects of prenatal and early life mal- of Height. J Polit Econ 2004;112:1019–53. nutrition: Evidence from the Greek famine. J Health Econ 73. Sargent JD, Blanchflower DG. Obesity and stature in adoles- 2011;30:479–88. cence and earnings in young adulthood: analysis of a British 53. Ju¨ rges H. Collateral damage: The German food crisis, educa- birth cohort. Arch Pediatr Adolesc Med 1994;148:681–87. tional attainment and labor market outcomes of German post- 74. Barker DJ, Eriksson J, Forsen T, Osmond C. Infant growth and war cohorts. J Health Econ 2013;32:286–303. income 50 years later. Arch Dis Child 2005;90:272–73. 54. Lumey L, Stein AD, Kahn HS, et al. Cohort profile: The Dutch 75. Schultz TP. Wage rentals for reproducible human capital: evi- Hunger Winter families study. Int J Epidemiol dence from Ghana and the Ivory Coast. Econ Hum Biol 2007;36:1196–204. 2003;1:331–66. 55. Maccini S, Yang D. Under the Weather: Health, Schooling, and 76. Elu JU, Price GN. Ethnicity as a Barrier to Childhood and Economic Consequences of Early-Life Rainfall. Am Econ Rev Adolescent Health Capital in Tanzania: Evidence from the 2009;99:1006–26. Wage-Height Relationship. Afr Dev Rev 2013;25:1–13. 56. Kesternich I, Siflinger B, Smith JP, Winter JK. The Effects of 77. Bo¨ ckerman P, Vainiomaki€ J. Stature and life-time labor market World War II on Economic and Health Outcomes across outcomes: Accounting for unobserved differences. Labour Europe. Rev Econ Stat 2014;96:103–18. Econ 2013;24:86–96. 57. Rosenzweig MR, Wolpin KI. Natural ‘natural experiments’ in 78. Yimer S, Fantaw O. The impacts of health and nutrition on economics. J Econ Lit 2000;827–74. wages in Ethiopia. Afr J Bus Manag 2011;5:12174–83. 58. Lundborg P, Nystedt P, Rooth D-O. Height and earnings: The 79. Elu JU, Price GN. Does Ethnicity Matter for Access to role of cognitive and noncognitive skills. J Hum Resour Childhood and Adolescent Health Capital in China? 2014;49:141–66. Evidence from the Wage-Height Relationship in the 2006 59. Alderman H, Hoddinott J, Kinsey B. Long term consequences China Health and Nutrition Survey. Rev Black Polit Econ of early childhood malnutrition. Oxf Econ Pap 2006;58: 2013;40:315–39. 450–74. 80. Gao W, Smyth R. Health human capital, height and wages in 60. Alderman H, Hoogevee, H, Rossi M. Preschool nutrition and China. J Dev Stud 2010;46:466–84. subsequent schooling attainment: longitudinal evidence from 81. Haddad LJ, Bouis HE. The impact of nutritional status on agri- Tanzania. Econ Dev Cult Change 2009;57:239–60. cultural productivity: wage evidence from the Philippines. Oxf 61. Adair LS, Popkin BM, Akin JS, et al. Cohort Profile: The Cebu Bull Econ Stat 1991;53:45–68. longitudinal health and nutrition survey. Int J Epidemiol 82. Heineck G. Up in the skies? The relationship between body 2011;40:619–25. height and earnings in Germany. Labour 2005;19:469–89. 62. Elliott J, Shepherd P. Cohort Profile: The 1970 British birth co- 83. Schultz TP. Wage Gains Associated with Height as a Form of hort (BCS70). Int J Epidemiol 2006;35:836–43. Health Human Capital. Am Econ Rev 2002;92:349–53. 20 International Journal of Epidemiology, 2017, Vol. 0, No. 0

84. Tao H-L. Height, weight, and entry earnings of female gradu- 105. African Union Commission/World Food Programme. The Cost ates in Taiwan. Econ Hum Biol 2014;13:85–98. of Hunger in Malawi: Social and Economic Impacts of Child 85. Thomas D, Strauss J. Health and wages: Evidence on men and Undernutrition in Malawi: Implications on National women in urban Brazil. J Econ 1997;77:159–85. Development and Vision 2020. Addis Ababa: African Union 86. Bo¨ ckerman P, Johansson E, Kiiskinen U, Helio¨ vaara M. The re- Commission, 2015. lationship between physical work and the height premium: 106. Bloom D, Cafiero-Fonseca ET, McGovern ME, et al. The Finnish evidence. Econ Hum Bio 2010;8:414–20. Macroeconomic Impact of Non-Communicable Diseases in 87. Case A, Paxson C. Causes and consequences of early-life China and India: Estimates, Projections, and Comparisons. J health. Demography 2010;47:S65–85. Econ Ageing 2014;4:100–11. 88. Eren,O, Ozbeklik S. The effect of noncognitive ability on the 107. Baten J. Heights and real wages in the 18th and 19th centuries: earnings of young men: A distributional analysis with measure- an international overview. Jahrb Fu¨ r Wirtsch Hist Yearb ment error correction. Labour Econ 2013;24:293–304. 2000;41:61–76. 89. Furnham A, Cheng H. Factors influencing adult earnings: 108. Bloom DE, Canning D, Sevilla J. The effect of health on eco- Findings from a nationally representative sample. J Socio-Econ nomic growth: a production function approach. World Dev 2013;44:120–25. 2004;32:1–13. 90. Heineck G. A note on the height–wage differential in the UK– 109. Chakraborty S, Papageorgiou C, Sebastian FP. Diseases, infec- Cross-sectional evidence from the BHPS. Econ Lett tion dynamics, and development. J Monet Econ 2010;57: 2008;98:288–93. 859–72. 91. Hu¨ bler O. The nonlinear link between height and wages in 110. Dalgaard C-J, Strulik H. The physiological foundations of the Germany, 1985–2004. Econ Hum Biol 2009;7:191–99. wealth of nations. J. Econ Growth 2015;20: 37–73. 92. Kortt M, Leigh A. Does Size Matter in Australia?. Econ Rec 111. Piper B. A production function examination of the aggregate ef- 2010;86:71–83. fects of nutrition. J Macroecon 2014;40:293–307. 93. Lindqvist,E. Height and leadership. Rev Econ Stat 112. Bleakley H. Health, human capital, and development. Annu 2012;94:1191–96. Rev Econ 2010;2:283. 94. Rashad I. Height, health, and income in the US, 1984–2005. 113. Weil DN. Health and economic growth. In: Aghion P, Durlauf Econ Hum Biol 2008;6:108–26. SN (eds). Handbook of Economic Growth. (2A). New York, 95. Rietveld CA, Hessels J, van der Zwan P. The stature of the self- NY: Elsevier, 2014. employed and its relation with earnings and satisfaction. Econ 114. Lopez-Casasnovas G, Rivera B, Currais L. Health and Hum Biol 2015;17:59–74. Economic Growth: Findings and Policy Implications. 96. Smith JP, Shen Y, Strauss J, Zhe Y, Zhao Y. The effects of child- Cambridge MA: MIT Press, 2005. hood health on adult health and SES in China. Econ Dev Cult 115. Well DN. Accounting for the Effect Of Health on Economic Change 2012;61:127. Growth. Q J Econ 2007;122:1265–306. 97. Sohn K. The height premium in Indonesia. Econ Hum Biol 116. Arora S. Health, human productivity, and long-term economic 2014;16:1–15. growth. J Econ Hist 2001;61:699–749. 98. Boo FL, Palloni G, Urzua S. Cost–benefit analysis of a micro- 117. Marıa-Dolores R, Martınez-Carrion JM. The relationship be- nutrient supplementation and early childhood stimulation tween height and economic development in Spain, 1850–1958. program in Nicaragua. Ann N Y Acad Sci 2914;1308: Econ Hum Biol 2011;9:30–44. 139–48. 118. Akachi Y, Canning D. Inferring the economic standard of 99. Horton S, Hoddinott J. Benefits and Costs of the Food and living and health from cohort height: Evidence from modern Nutrition Targets for the Post-2015 Development Agenda. populations in developing countries. Econ Hum Biol Copenhagen: Copenhagen Development Center, 2015. 2015;19:114–28. 100. Ross J, Chen C-M, He W, et al. Effects of malnutrition on eco- 119. Bershteyn A, Lyons HM, Sivam D, Myhrvold NP. Association nomic productivity in China as estimated by PROFILES. between economic growth and early childhood nutrition. Biomed Environ Sci 2003;16:195–205. Lancet Glob Health 2015;3:e79–80. 101. Alcazar L, Ocampo D, Huaman-Espino L, Pablo Aparco J. 120. Vollmer S, Harttgen K, Subramanyam MA, Finlay J, Klasen S, Economic impact of chronic, acute and global Subramanian S. Association between economic growth and malnutrition in Peru. Rev Peru Med Exp Salud Publica early childhood undernutrition: evidence from 121 2013;30:569–74. Demographic and Health Surveys from 36 low-income and 102. Bagriansky J, Champa N, Pak K, Whitney S Laillou A. The eco- middle-income countries. Lancet Glob Health nomic consequences of malnutrition in Cambodia, more than 2014;2:e225–34. 400 million US dollar lost annually. Asia Pac J Clin Nutr 121. Headey DD. Developmental drivers of nutritional change: a 2014;23:524. cross-country analysis. World Dev 2013;42:76–88. 103. Horton,S, Ross J. The economics of iron deficiency. Food 122. Heltberg R. Malnutrition, poverty, and economic growth. Policy 2003;28:51–75. Health Econ 2009;18:S77–88. 104. Fernandez A, Martınez R. Model for Analysing the Social and 123. Ruel MT, Alderman H; Maternal and Child Nutrition Study Economic Impact of Child Undernutrition in Latin America. Group. Nutrition-sensitive interventions and programmes: how Santiago: United Nations Economic Commission for Latin can they help to accelerate progress in improving maternal and America and the Caribbean (ECLAC), 2007). child nutrition?. Lancet 2013;382:536–51. International Journal of Epidemiology, 2017, Vol. 0, No. 0 21

124. Harttgen K, Klasen S, Vollmer S. Economic Growth and Child 136. Fink G, Gu¨ nther I, Hill K. The effect of water and sanitation on Undernutrition in sub-Saharan Africa. Popul Dev Rev child health: evidence from the Demographic and Health 2013;39:397–412. Surveys 1986–2007. Int J. Epidemiol 2011;40:1196–204. 125. Webb P, Block S. Support for agriculture during economic 137. Alderman H, Hoogeveen H, Rossi M. Reducing child malnutri- transformation: Impacts on poverty and undernutrition. Proc tion in Tanzania: Combined effects of income growth and pro- Natl Acad Sci 2012;109:12309–14. gram interventions. Econ Hum Biol 2006;4:1–23. 126. Smith LC, Haddad L. How Potent Is Economic Growth in 138. Haddad,L. Equity: Not Only for Idealists. Dev Policy Rev Reducing Undernutrition? What Are the Pathways of Impact? 2015;33:5–13. New Cross-Country Evidence. Econ Dev Cult Change 139. Florêncio TT, Ferreira HS, Cavalcante JC, Assuncao M, Sawaya 2002;51:55–76. AL. Short stature and food habits as determining factors for the 127. Haddad L, Alderman H, Appleton S, Song L, Yohannes Y. low productivity of sugarcane labourers in the State of Alagoas, Reducing child malnutrition: How far does income growth take north-eastern Brazil. Arch Latinoam Nutr 2008;58:33–9. us?. World Bank Econ Rev 2003;17:107–31. 140. Price GN. The allometry of metabolism and stature: Worker fa- 128. Subramanyam MA, Kawachi I, Berkman LF, Subramanian S. Is tigue and height in the Tanzanian labor market. Econ Hum economic growth associated with reduction in child undernutri- Biol 2013;11:515–21. tion in India?. PLoS Med 2011;8:448. 141. Doyle O, Harmon CP, Heckman JJ, Tremblay RE. Investing in 129. Moradi A. Nutritional status and economic development in early human development: timing and economic efficiency. sub-Saharan Africa, 1950–1980. Econ Hum Biol Econ Hum Bio 2009;7:1–6. 2010;8:16–29. 142. Krzyzanowska_ M, Mascie-Taylor CN. Intra-and intergenera- 130. Vollmer S, Harttgen K, Subramanyam MA, Finlay J, Klasen S, tional social mobility in relation to height, weight and body Subramanian S. Association between economic growth and mass index in a British national cohort. J Biosoc Sci early childhood nutrition–Authors’ reply. Lancet Glob Health 2011;43:611–18. 2014;2:e501–02. 143. Steckel RH. Biological measures of the standard of living. J 131. Alderman H, Haddad L, Headey DD, Smith L. Association be- Econ Perspect 2008;22:129–52. tween economic growth and early childhood nutrition. Lancet 144. Yousafzai AK, Rasheed MA, Rizvi A, Armstrong R, Bhutta Glob Health 2014;2:e500. ZA. Effect of integrated responsive stimulation and nutrition 132. Cavatorta E, Shankar B, Flores-Martinez A. Explaining Cross- interventions in the Lady Health Worker programme in State Disparities in Child Nutrition in Rural India. World Dev Pakistan on child development, growth, and health outcomes: a 2015;76:216–37. cluster-randomised factorial effectiveness trial. Lancet 133. International Food Policy Research Institute. Global Nutrition 2014;384:1282–93. Report 2014: Actions and Accountability to Accelerate the 145. Haddad L, Masset E, Smith L. Does The Quality of Income World’s Progress on Nutrition. Washington, DC: International Growth Affect Child Nutrition Status? In: Haddad L, Kato H, Food Policy Research Institute, 2014. Meisel N (eds). Growth is Dead, Long Live Growth: The 134. International Food Policy Research Institute. Global Nutrition Quality of Economic Growth and Why it Matters. Paris: Report 2015: Actions and Accountability to Advance Nutrition Agence Française de De´veloppement (AFD), Brighton, UK: and Sustainable Development. Washington, DC: International Institute of Development Studies (IDS), Tokyo: Japan Food Policy Research Institute, 2015. International Cooperation Agency (JICA), 2015. 135. Aguayo VM, Menon P. Stop stunting: improving child feeding, 146. Jenkins JM. Early Childhood Development as Economic women s nutrition and household sanitation in South Asia. Development Considerations for State-Level Policy Innovation Matern Child Nutr 2016;12(S1):3–11. and Experimentation. Econ Dev Q 2014;28:147–65.