Survival of the Weakest? Culling Evidence from the 1918 Flu Pandemic

University of Zurich, Department of Economics, Working Paper No. 316

38 Pages Posted: 12 Feb 2019

See all articles by Joël Floris

Joël Floris

University of Zurich

Laurent Kaiser

Geneva University Hospitals and Faculty of Medicine - Division of Infectious Diseases

Harald Mayr

University of Zurich

Kaspar Staub

University of Zurich

Ulrich Woitek

University of Zurich

Date Written: January 30, 2019

Abstract

When a negative shock affects a cohort in utero, two things may happen: first, the population suffers detrimental consequences in later life; and second, some will die as a consequence of the shock, either in utero or early in life. The latter effect, often referred to as culling, may induce a bias in estimates of later life outcomes. When the health shock disproportionately affects a positively selected subpopulation, the long-term effects are overestimated. The 1918 flu pandemic was plausibly more harmful to mothers of high socioeconomic status, as a suppressed immune system in mothers of low socioeconomic status may have been protective against the most severe consequences of infection. Using historical birth records from the city of Bern, Switzerland, we assess this concern empirically and document that a careful consideration of culling is paramount for the evaluation of the 1918 flu pandemic and other fetal health shocks.

Keywords: Fetal origins hypothesis, 1918 flu pandemic, culling, survivorship bias

JEL Classification: I10, I15, I18, N34, J24

Suggested Citation

Floris, Joël and Kaiser, Laurent and Mayr, Harald and Staub, Kaspar and Woitek, Ulrich, Survival of the Weakest? Culling Evidence from the 1918 Flu Pandemic (January 30, 2019). University of Zurich, Department of Economics, Working Paper No. 316, Available at SSRN: https://ssrn.com/abstract=3326517 or http://dx.doi.org/10.2139/ssrn.3326517

Joël Floris (Contact Author)

University of Zurich ( email )

Rämistrasse 71
Zürich, CH-8006
Switzerland

Laurent Kaiser

Geneva University Hospitals and Faculty of Medicine - Division of Infectious Diseases ( email )

Geneva
Switzerland

Harald Mayr

University of Zurich

Rämistrasse 71
Zürich, CH-8006
Switzerland

Kaspar Staub

University of Zurich ( email )

Rämistrasse 71
Zürich, CH-8006
Switzerland

Ulrich Woitek

University of Zurich ( email )

Zürichbergstrasse 14
CH-8032 Zurich
Switzerland

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