Early-life Influences and the Seasonality of Mortality: Re-Examining the Doblhammer Effect

Andrew Noymer, University of California, Irvine
Bert Kestenbaum, U.S. Social Security Administration (SSA)

Doblhammer and Vaupel (2001) showed that length of life depends on month of birth. This had major implications for the debate on early-life influences on later-life health and mortality. If the early-life influences hypothesis is correct, length of life is influenced by events circa 75 years prior. This paper extends the work of Doblhammer by considering more recent data of comparable sample size. We find that the effect of month of birth (a proxy for in-utero conditions, including exposure to cold-and-flu season viruses as well as micronutrient deficiencies) on month of death diminishes in more recent data. This adds an important dimension, as it suggests that micronutrient deficiencies, which were seasonal but which diminished over time, and not viruses (which circulate every winter, even now), account for the Doblhammer effect. Our use of more recent data permits important differentiation.