Dramatic improvements in life expectancy during the 20th century are commonly attributed to improvements in either health care services or the social and economic environment. We evaluated the hypothesis that improving infant survival produces improvements in adult (40 years) mortality rates. We used generalizations of age-period-cohort models of mortality that explicitly account for the exponential increase of adult mortality rates with age (Gompertz model) to determine whether year of birth or year of death better correlate with observed patterns of adult mortality. We used data from Canada and nine other countries obtained from the Human Mortality Database. Five-year birth cohorts between 1900 and 1944 showed consistent improvements in age-specific mortality rates. According to the akaike information criteria, Gompertz-Cohort models significantly better predicted the observed patterns of adult mortality than Gompertz-Period models, demonstrating that year of birth correlates better with adult mortality than year of death. Infant mortality strongly correlated with the initial set point of adult mortality in a Gompertz-period-cohort. Selected countries exhibited elevated adult mortality rates for the 1920 and 1944 birth cohorts, suggesting that the period before the first year of life may be uniquely vulnerable to environmental influences. These findings suggest that public health investments in the health of mothers and children can be a broad primary prevention strategy to prevent the chronic diseases of the adult years.
(Received November 02 2009)
(Revised February 17 2010)
(Accepted April 12 2010)
(Online publication May 10 2010)
Key wordsadult mortality patterns; birth-cohort effects; Gompertz mortality; infant and fetal conditions