Secular Trends of Sudden Infant Death Syndrome and Other Causes of Post Perinatal Mortality in Norwegian Birth Cohorts 1967–1984

Abstract
Lack of positive diagnostic criteria and increasing professional concern, probably causing increasing ascertainment, have rendered reported increases in SIDS-rates controversial. However, these problems related to cause specific mortality do not apply to the total mortality. Due to the exceptional age-at-death distribution of SIDS cases, the SIDS fraction of all deaths increases during the first year of life to reach a maximum, in the present study of 56%, from the 105th through the 125th day of life. During these days, the total mortality rate in Norway increased from 0.24 per 1000 in 1971-72 to 0.46 in 1983-84. Thus, the observed trend, with an increase in the SIDS rate from 1.02 per 1000 in 1971-72 to 2.34 in 1983-84, is considered true. Observed in a country where perinatal and neonatal mortality have decreased for a long period of time and still remain very low in a global perspective, the increasing SIDS rate is a matter of great concern.