The long-term impact of intrauterine exposure to malnutrition



A constantly recurring question is how decades of chronic food insecurity interspersed with food emergencies and even outright famine may affect the long-term physical and mental health of the North Korean people.  Since we cannot do direct scientific study of the North Korean population, thinking on this issue is by its very nature speculative.

One way of getting at the issue is to examine the emerging scientific literature on the impact of nutrition on later life outcomes derived from the experiences of other countries.  Last year I reviewed a paper by George Mason University economists Sven Neelsen and Thomas Stratmann on the impact of early life famine exposure derived from Greek data. Today I look at a paper passed along by Nick Eberstadt written by Max Planck Institute economist Hendrik Jürges that exploits both time-series and cross-sectional variation in data from Germany and Austria to examine the impact of intrauterine exposure to malnutrition on later life outcomes. The paper has been published in the Journal of Health Economics; it is also available in working paper form.

Jürges documents a sharp fall in food availability in Germany and Austria coinciding with the end of the Second World War.  In Germany, caloric intake for both sexes plunged from 2,500 calories per day during the early war years, to a minimum of 350 in May 1945, before rising back to normal over the next several years.  Protein intake plunged and recovered along a similar pattern. Infant mortality peaked during the period March-May 1945, reaching 20 percent, four times the pre-war average. In localities for which monthly data is available, birth weights followed a similar pattern, reaching a minimum in the spring of 1945. Monthly data together with the sharpness of the decline, allows Jürges to pinpoint the impact of intrauterine exposure to malnutrition which he then correlates with educational attainment and labor market outcomes using German census data from 1970 and 1987, and Austrian data from 1971, 1981, 1991, and 2001.

Clearly, the food crisis was not the only thing going on in Germany and Austria during 1945.  Jürges also examines the possible impact due to voluntary and involuntary migration from the eastern parts of the Third Reich and the Sudetenland; rapes, mainly by Red Army soldiers; and the likelihood of self-selection in pregnancy (also an issue in the Greek case) in which the better off are more likely to conceive during crisis periods, biasing the results against finding a famine effect. Jürges finds that conceptions during the latter stages of the war occurred disproportionately among high education males and females, not only due to intentional self-selection, also observed in Greece, but also because of selective exemption of highly educated males from serving on either the Eastern or Western fronts.

Yet using various approaches to control for these effects, he obtains results that are generally statistically significant for both men and women for educational attainment, employment, job classification, and earnings. The impact appears to be the most severe on later life outcomes for maternal exposure to malnutrition during the first trimester. The magnitude of the effects are not huge, though as in the case of the Neelsen and Stratmann paper on Greece, the selective pregnancy self-selection bias, as well as some other sources of bias, would steer the results toward finding small effects.  In other words, in terms of impact, Jürges has identified a floor not a ceiling.

So what does this mean for North Korea?  The basic thrust of the paper is that maternal nutritional status really matters during the first trimester. We still do not know much about how nutritional status evolved during the famine or in recurrent contractions in food availability since 1998, though Witness to Transformation and our earlier work on the famine document a remarkably rapid collapse of the public distribution system in the early 1990s. If the downturns are relatively gradual, then the normal pattern of delaying pregnancies may cushion the deleterious effects. However, if the downturns are precipitous, or if societal coping or implicit insurance mechanisms are frayed, then by implication chronic food insecurity in North Korea may be generating cohort after cohort of individuals with compromised life chances.

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