Competing Effects on the Average Age of Infant Death

Leslie Root , University of California, Berkeley
Monica Alexander, University of Toronto

In recent decades, the relationship between the average length of life for those who die in the first year of life – the lifetable quantity 1a0 – and the level of infant mortality, on which its calculation is often based, has broken down. The very low levels of infant mortality in the developed world correspond to a range of 1a0 quantities. We illustrate the competing effect of falling mortality and reduction in preterm births on 1a0, through simulation and through an example with US data on two populations with very different levels of premature birth – infants born to non-Hispanic white mothers and to non-Hispanic black mothers. We demonstrate that falling mortality reduces 1a0 while fewer premature births increase it. Future work will focus on utilizing these observations in developing an alternative formula for 1a0, which aims to capture not only the level of infant mortality, but also the level of prematurity.

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 Presented in Session 15. Mortality Models