Age at neonatal death in Ontario, 1979–1987: implications for the interpretation of mortality markers

Summary. Recent evidence concerning time trends in infant mortality rates suggests faster falls in early compared with late deaths. This may be due to rapid advances in neonatal care. This study was undertaken to examine the timing of neonatal death in Ontario between 1979 and 1987. Trends with time, gestational age and type of birth hospital were examined. Evidence suggests that, controlling for level of birth hospital and gestational age, there was a time trend of an increasing proportion of late neonatal deaths. This suggests that early neonatal mortality was decreasing more rapidly than late neonatal mortality. Controlling for year of birth and gestational age, it was observed that the proportion of late neonatal deaths was higher for those born in a tertiary rather than community hospital. In combination, these findings suggest that, due to advances in neonatal care, a disproportionately high number of early neonatal deaths are increasingly being prevented. The findings have implications for the interpretation of routinely available mortality markers. The authors conclude that early neonatal death rate may be becoming a less useful marker and that a measure of perinatal mortality which includes late neonatal deaths would be a useful addition to the currently collected mortality markers.