Average Age at Death in Infancy: Reconsidering the Coale-Demeny Formulas at Current Levels of Low Mortality

Evgeni Andreev, Max Planck Institute for Demographic Research
Ward Kingkade

The historical decline in infant mortality has led to concentration of infant deaths in earliest infancy. The influence of prenatal and neonatal conditions has become increasingly dominant relative to postnatal conditions as infant mortality has declined. In the mid-1960s Coale and Demeny developed formulas describing the relationship between the average age of death in infancy and the level of infant mortality. Subsquent to Coale and Demeny’s analysis, rises in the average age of infant death commenced in low-mortality countries. We investigate this phenomenon using several data sources, including the linked birth and infant death datasets from the US National Center for Health Statistics, and international data from the Human Mortality Database and the WHO. An explanation for the increase in average age of death in infancy in terms of cause of death is proposed, and modifications of the Coale-Demeny formulas for application under contemporary low levels of mortality are offered.