This study uses the 1918-1920 influenza pandemic in Japan with newly digitized
and complete census records on births, infant deaths, and sex ratios during childhood to analyze mortality selection in utero and its persistency in the gender imbalance.
We find that fetal exposure to pandemic influenza during the first trimester of the
pregnancy ...
(Show more)This study uses the 1918-1920 influenza pandemic in Japan with newly digitized
and complete census records on births, infant deaths, and sex ratios during childhood to analyze mortality selection in utero and its persistency in the gender imbalance.
We find that fetal exposure to pandemic influenza during the first trimester of the
pregnancy period decreased the proportion of males at birth in this period. We
then show that the decline in male births might have been associated with the
deterioration of fetal health due to pandemic influenza. Analyses using Population
Censuses provide evidence suggesting that postnatal influenza exposure had long-term
impacts on the sex ratio of children aged 5-12.
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