Declining perinatal mortality in Finland between 1987 and 1994: contribution of different subgroups.

Objective: To examine the extent to which the decline in perinatal mortality is attributable to some subgroups, especially to certain birthweight or gestation groups.

Methods: A register study using the Finnish Medical Birth Register for years 1987 to 1994.

Results: Of the overall reduction in perinatal mortality from 8.8 to 6.7 per 1000 births, 78% was due to stillbirths, compared with 22% due to early neonatal deaths. The decline in mortality among infants who weighed under 1500 g at birth was the major contributor (62%) to the overall reduction in perinatal mortality. The largest decline in mortality in the stillbirth group occurred among those weighing < 1000 g, while for early neonatal deaths the group most affected weighed 1000-1499 g. A similar pattern emerged when the gestation-week groups were examined.

Conclusions: The decline in perinatal mortality is attributable to stillbirths of very low birthweight. The most likely explanations for this result are the improved antenatal and neonatal care and the wider use of malformation screening.