Causal Link:

1918 influenza pandemic a “natural experiment” testing “fetal origins hypothesis” on adults socio-economic outcomes.

Identification:

First, the pandemic struck without warning in October 1918 and had largely dissipated by the beginning of 1919 implying that cohorts born just months apart experienced markedly different in-utero conditions.

Second,the severity of the pandemic varied widely and idiosyncratically across states.

Identification fails if :

In order to bias estimates, omitted factors would have to follow the same abrupt and idiosyncratic patterns as the pandemic.

A. 1960-80 Census Micro Data

• influenza birth cohorts
• identify state of birth
• 1960, 1970, and 1980 data: analysis using birth quarter & year

Econometric Framework

Econometric Framework

utilize geographic variation: differences in the severity of the pandemic as measured by mortality.

• Adult outcomes modeled as a function of maternal influenza infection rates.

• Identification of \(\hat{\psi}_s\) comes from differential changes in state infection rates around the pandemic average (one-third) immediately before and after the pandemic’s peak.