The 1918 influenza pandemic struck the United States with most ferocity in October of 1918 and then over the next four months killed more people than all the US combat deaths of the 20th century. The sudden nature of the pandemic meant that children born just months apart experienced very different conditions in utero. In particular, children born in 1919 were much more exposed to influenza in utero than children born in 1918 or 1920. The sudden differential to the 1918 flu lets Douglas Almond test for long-term effects in Is the 1918 Influenza Pandemic Over?
Almond finds large effects many decades after exposure.
Fetal health is found to affect nearly every socioeconomic outcome recorded in the 1960, 1970, and 1980 Censuses. Men and women show large and discontinuous reductions in educational attainment if they had been in utero during the pandemic. The children of infected mothers were up to 15% less likely to graduate from high school. Wages of men were 5–9% lower because of infection. Socioeconomic status…was substantially reduced, and the likelihood of being poor rose as much as 15% compared with other cohorts. Public entitlement spending was also increased.
…male disability rates in 1980, ie. for males around the age of 60, by year and quarter of birth. Cohorts born between January and September of 1919 “were in utero at the height of the pandemic and are estimated to have 20% higher disability rates at age 61…”.
Figure 3 at right shows average years of schooling in 1960; once again the decline is clear for those born in 1918 and note that not all pregnant women contracted influenza so the actual effects of influenza exposure are larger, about a 5 month decline in education, mostly coming through lower graduate rates.