[The evolution of mortality in the first year of life in Spain (1975-1988)]

In recent years, the rate of decline in infant mortality and the proportional mortality by some causes of death in the first year of life have had important changes. The objectives of this study are to describe such changes, and to suggest hypotheses about their meaning. Infant, early neonatal, late neonatal and postneonatal mortality rates from 1975 to 1988 were calculated with information from the death register. Also, several indicators of the trends of those rates and proportional mortality by "certain conditions originating in the perinatal period" have been calculated. The reduction in infant mortality was due, mainly, to early neonatal mortality, which had an annual average decline of 4.6% during the study period. The proportional mortality and the mortality rate by perinatal conditions in the postneonatal period increased between 1975 and 1988. The first increased from 1.3% to 5.2%, and the second from 0.07 to 0.15 per 1000 live births. Hypotheses about the meaning of these results are suggested, and some actions are proposed in order to monitor and conduct research on mortality during the first year of life.