The Long-Lasting Influenza: The Impact of Fetal Stress During the 1918 Influenza Pandemic on Socioeconomic Attainment and Health in Sweden, 1968-2012

Abstract

The 1918 influenza pandemic had not only a massive instant death toll but also lasting effects on its survivors. Several studies have shown that children born in 1919, and thus exposed to the H1N1 virus in utero, experienced worse health and socioeconomic outcomes in older ages than surrounding birth cohorts. This study combines several sources of contemporary statistics with full-population individual-level data for Sweden during 1968-2012 to examine the influence of fetal exposure to the Spanish flu on health, adulthood income, and occupational attainment. For both men and women, fetal exposure resulted in higher morbidity in ages 54-87, as measured by hospitalization. For males, exposure during the second trimester also affected mortality in cancer and heart disease. Overall, the effects on all-cause mortality were modest, with about three months shorter remaining life expectancy for the cohorts exposed during the second trimester. For socioeconomic outcomes, results fail to provide consistent evidence supporting any long-term consequences of fetal exposure. We conclude that although the immediate health effects of exposure to the 1918 pandemic were huge, the long-term effects were modest in size.

Keywords: Fetal origins; Health and socioeconomic outcomes; Longitudinal data; Spanish influenza pandemic; Sweden.

Fig. 1

Stillbirths per 1,000 live births, by month. Sweden, 1914–1925. The shaded vertical bars represents the period October–December 1918. Source: Sveriges Officiella Statistik: Befolkningsrörelsen 1914–1925.

Fig. 2

Infant deaths due to malformations and disease, expressed as a share per 1,000 live births during current month, 1914–1925. The shaded vertical bars represents the period October–December 1918. Source: Sveriges Officiella Statistik: Befolkningsrörelsen 1914–1925 and Dodsorsaker 1914–1925.

Fig. 3

Log mean income and mean CAMSIS score in 1970, by birth year and quarter. CAMSIS ranges from 1 to 99, with higher scores indicating higher occupational attainment. The shaded vertical bar represents individuals born during Quarter 1, 1919. Source: Swedish Interdisciplinary Panel.

Fig. 4

Share hospitalized during current year, by birth year and quarter. The shaded vertical bar represents individuals born during Quarter 1, 1919. Source: Swedish Interdisciplinary Panel.

Fig. 5

Mean age at death, by birth year and quarter. The shaded vertical bar represents individuals born during Quarter 1, 1919. Source: Swedish Interdisciplinary Panel.