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Changing speed of reduction in under-5 mortality rates over the 20th century
  1. Omar Karlsson1,2,3,
  2. Martin Dribe2,3,
  3. S V Subramanian4,5
  1. 1 Takemi Program in International Health, Harvard University T H Chan School of Public Health, Boston, Massachusetts, USA
  2. 2 Centre for Economic Demography, Lund University School of Economics and Management, Lund, Sweden
  3. 3 Department of Economic History, Lund University School of Economics and Management, Lund, Sweden
  4. 4 Department of Social and Behavioral Sciences, Harvard University T H Chan School of Public Health, Boston, Massachusetts, USA
  5. 5 Harvard Center for Population and Development Studies, Cambridge, Massachusetts, USA
  1. Correspondence to Omar Karlsson, Takemi Program in International Health, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, Boston MA 02115, USA; okarlsson{at}


Background Declines from high levels of under-5 mortality rate (U5MR) first occurred in Western Europe. Knowledge and technologies gained from early mortality reductions could accelerate the U5MR decline for countries that followed. We explored whether average annual reduction (AAR) in U5MR increased between countries over time in the 20th century.

Methods We used U5MR time series from the Human Mortality Database and United Nations for 110 countries experiencing a decline from 100 to 50 under-5 deaths per 1000 live births during the 20th century.

Results Between 1907 and 1938, the AAR was 2.61 (95% CI 2.09, 3.13) deaths per 1000 live births per year on average and increased by 0.06 (95% CI 0.02, 0.10) deaths for each year that passed before the decline started. Countries going through the decline in 1938–1968 and 1968–1999 showed an AAR of 3.96 and 3.67 (95% CI 3.37, 4.54 and 3.26, 4.07), respectively, with no increase in AAR.

Conclusions Acceleration in U5MR reduction was apparent in today’s high-income countries, indicating that greater similarities and capacity may have facilitated the adaptation of mortality reducing knowledge and technologies. Greater emphasis on simple and individual-level interventions or more difficult circumstances may also explain the lack of acceleration in mortality reduction after 1950.


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  • Correction notice This article has been corrected since it first published online. Figure 1 has been corrected, and the previous version of the supplemental file removed.

  • Contributors All authors contributed to the study concept and design, the interpretation of findings and the drafting of the manuscript. OK acquired the data and performed the analysis. OK is the guarantor for the overall content of this article. All authors approved the final version of the submitted manuscript.

  • Competing interests None declared.

  • Patient consent for publication Not required.

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

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