A sick mother will make a sick baby who becomes a sick adult

As much as we’d like to believe it, babies aren’t a blank slate. Babies not only bear the social and economic legacies of the families which produce the, but also the scars of a lifetime of immunological insults.

This week, a paper, “Does in utero Exposure to Illness Matter? The 1918 Influenza Epidemic in Taiwan as a Natural Experiment,” appeared in the journal of the National Bureau of Economic Research which tracks the long term effects of the 1918-1920 worldwide influenza pandemic.

Turns out that babies which were born to mothers in that period were, on average, shorter than people born in other years, had more developmental problems, and, possibly, suffered from long term problems of chronic disease.

This paper tests whether in utero conditions affect long-run developmental outcomes using the 1918 influenza pandemic in Taiwan as a natural experiment. Combining several historical and current datasets, we find that cohorts in utero during the pandemic are shorter as children/adolescents and less educated compared to other birth cohorts. We also find that they are more likely to have serious health problems including kidney disease, circulatory and respiratory problems, and diabetes in old age. Despite possible positive selection on health outcomes due to high infant mortality rates during this period (18 percent), our paper finds a strong negative impact of in utero exposure to influenza.

It’s interesting to me, in that it’s a study of health on one of Japan’s former colonies, but also because Taiwan’s indicators in 1918 were atrocious. More than a fifth of babies didn’t live to see their fifth birthday, deaths in childbirth were common and life was short. In other words, it’s a lot like a lot of African contexts today.

The long term outcomes of common developing world diseases have mostly been ignored. There is every reason to believe that one of the reasons African countries suffer economically is that people’s developmental trajectory is set before even exiting the womb. SO we’re fighting against not only a bleak economic past, but also against a constant legacy of infectious insults.

And to moms in the developed world…. get your flu shots.