Objective: To provide a valid estimate of singleton neonatal mortality based on birthweight and gestational age at delivery.
Design: Record linkage of maternity data and neonatal mortality data.
Setting: Scotland, UK.
Population: All singleton preterm deliveries from 24 to 36 weeks inclusive between 1985 and 1994.
Main outcome measure: Neonatal death.
Results: There were 625,646 liveborn singleton deliveries over the study period, of which 33,912 were preterm (5.4%). The overall neonatal mortality in the preterm group was 41/1000 and the data have been presented by both gestational age and birthweight. The neonatal mortality rate fell with advancing gestation from 795/1000 live births at 24 weeks to 9/1000 live births at 36 weeks and was higher at the extremes of birthweight for a given gestational age. There was a significant increase in the proportion of babies delivered iatrogenically over the study period (chi test for trend P < 0.001).
Conclusion: This is the largest recent series to consider neonatal mortality using both birthweight and gestational age. These figures will be of use in obstetric management when elective preterm delivery is considered, and for providing prognostic guidance following preterm delivery.