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Original research
Income inequality and social gradients in children’s height: a comparison of cohort studies from five high-income countries
  1. Philippa K Bird1,2,
  2. Kate E Pickett1,
  3. Hilary Graham1,
  4. Tomas Faresjö3,
  5. Vincent W V Jaddoe4,5,
  6. Johnny Ludvigsson6,
  7. Hein Raat7,
  8. Louise Seguin8,
  9. Anne I Wijtzes7,
  10. Jennifer J McGrath9
  1. 1 Department of Health Sciences, University of York, York, North Yorkshire, UK
  2. 2 Leeds Teaching Hospitals NHS Trust, Leeds, UK
  3. 3 Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
  4. 4 Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands
  5. 5 Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands
  6. 6 Division of Pediatrics, Medical Faculty, Linköping University, Linköping, Sweden
  7. 7 Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands
  8. 8 Department of Social and Preventive Medicine, Universite de Montreal, Montreal, Québec, Canada
  9. 9 Department of Psychology, Concordia University, Montreal, Québec, Canada
  1. Correspondence to Dr Philippa K Bird; philippa.bird{at}


Background Health and well-being are better, on average, in countries that are more equal, but less is known about how this benefit is distributed across society. Height is a widely used, objective indicator of child health and predictor of lifelong well-being. We compared the level and slope of social gradients in children’s height in high-income countries with different levels of income inequality, in order to investigate whether children growing up in all socioeconomic circumstances are healthier in more equal countries.

Methods We conducted a coordinated analysis of data from five cohort studies from countries selected to represent different levels of income inequality (the USA, UK, Australia, the Netherlands and Sweden). We used standardised methods to compare social gradients in children’s height at age 4–6 years, by parent education status and household income. We used linear regression models and predicted height for children with the same age, sex and socioeconomic circumstances in each cohort.

Results The total analytic sample was 37 063 children aged 4–6 years. Gradients by parent education and household income varied between cohorts and outcomes. After adjusting for differences in age and sex, children in more equal countries (Sweden, the Netherlands) were taller at all levels of parent education and household income than children in less equal countries (USA, UK and Australia), with the greatest between-country differences among children with less educated parents and lowest household incomes.

Conclusions The study provides preliminary evidence that children across society do better in more equal countries, with greatest benefit among children from the most disadvantaged socioeconomic groups.

  • epidemiology
  • growth

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  • Contributors PKB contributed to the study design, conducted the data analysis and literature search and drafted the report. KEP and HG contributed to the study design, interpretation of findings and writing of the report. TF, VWVJ, JL, HR, LS, AIW and JJM contributed to access to the cohort data, harmonisation of data, interpretation of findings and writing the report. All authors edited the report and approved the final draft.

  • Funding This work was primarily supported by a doctoral training studentship from the UK Economic and Social Research Council. Further support was provided by grants awarded by the Canadian Institutes of Health Research (#MSH95353, #MOP123533, #00309MOP-123079). This project received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement 733206 (LifeCycle Project). The Early Child Longitudinal Study K cohort is managed by the National Center for Education Statistics, US Department of Education. For the Millennium Cohort Study, we are grateful to the Centre for Longitudinal Studies, Institute of Education for the use of these data and to the UK Data Archive and Economic and Social Data Service for making them available. However, they bear no responsibility for the analysis or interpretation of these data. The Longitudinal Study of Australian Children was initiated and is funded by the Australian Government Department of Families, Housing, Community Services and Indigenous Affairs, and is undertaken in partnership with the Australian Institute of Family Studies and the Australian Bureau of Statistics. The Generation R Study (GenerationR) is conducted by the Erasmus Medical Center, Rotterdam in close collaboration with the School of Law and Faculty of Social Sciences of the Erasmus University Rotterdam, the Municipal Health Service Rotterdam area, the Rotterdam Homecare Foundation and the Stichting Trombosedienst en Artsenlaboratorium Rijnmond, Rotterdam. We gratefully acknowledge the contribution of general practitioners, hospitals, midwives and pharmacies in Rotterdam. The first phase of the GenerationR was made possible by financial support from the Erasmus Medical Center, Rotterdam, the Erasmus University Rotterdam and the Netherlands Organisation for Health Research and Development. We are grateful to the All Babies in Southeast Sweden (ABIS) team at Linkoping University, all families, well-baby clinics and schools. ABIS has been funded by Swedish Research Council (No. K2009-70X-21086-01-3), grants from The Swedish Council for Working Life and Social Research (No. 2008-0284), Medical Research Council of Southeast Sweden, Swedish Child Diabetes Foundation (Barndiabetesfonden), Juvenile Diabetes Research Foundation and Research Council for Southeast Sweden.

  • Disclaimer The funders of the study had no role in the design of the study, collection, analysis and interpretation of data, or in writing this manuscript.

  • Competing interests TF, VWVJ, JL, HR, LS, AIW and JJM report no conflicts of interest. PKB reports funding from an Economic and Social Research Council (ESRC) doctoral studentship and the Canadian Institute for Health Research (CIHR). HG reports funding from an ESRC doctoral studentship. KEP reports grants from the ESRC during the conduct of the study, and is co-founder and trustee of The Equality Trust, which campaigns for greater income equality.

  • Patient and public involvement statement As analysis used secondary data only, no additional patient and participant involvement was conducted.

  • Patient consent for publication Not required.

  • Ethics approval The study involved analysis of secondary data only. All cohort studies had been reviewed and approved by appropriate ethics review boards and obtained informed consent from participants.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data from the MCS, ECLS and LSAC are available in a public, open access repository. Data from GenerationR and ABIS are available on request (;