Neonatal mortality and cerebral palsy: the impact of neonatal intensive care

Neonatal deaths and cases of cerebral palsy amongst West Australian infants born between 1968–75 were analysed by birthweight and in relation to other factors. Both mortality and cerebral palsy incidence fell over time. Male rates fell selectively more than those for females. A shift in the birthweight distribution of total live births to heavier babies accounted for 22% of the fall in neonatal mortality, and 56% of the fall in cerebral palsy incidence over this time. Although selective changes in the maternal age and parity of mothers delivering occurred, they were responsible for only a small per cent of the falls in either neonatal mortality or cerebral palsy. Other parameters of improved maternal health contributing to the falls could not be ascertained. Maternal age and parity are still strongly associated with mortality. Cerebral palsy incidence was not associated with age, but was markedly higher at the high parities. The most important findings related to neonatal mortality and cerebral palsy rates by birthweight. Neonatal mortality improved in all weight groups, only slightly more in the low, compared with the high birthweight babies. Cerebral palsy incidence however, improved most markedly in the heavier babies and thus those of low birthweight contributed relatively more to the cerebral palsy population recently than before neonatal intensive care was introduced. Thus the impact of neonatal intensive care on the low birthweight population in Western Australia has been mainly in terms of neonatal mortality. Other factors besides intensive care have obviously contributed to the observed falls in both mortality and cerebral palsy.