Cerebral palsy--trends in incidence and changes in concurrent neonatal mortality: Rochester, MN, 1950-1976.

We studied all identified cases of cerebral palsy (CP) born to residents of Rochester, MN, during a 27-year period. Incidence rates per 1,000 neonatal survivors were computed for three 9-year intervals. For children with persisting findings, the incidence rate of all syndromes declined from 2.3 to 1.6. For spastic syndromes, this trend was more marked (2.1 to 0.9). For newborns with birthweight over 2,500 g, both CP incidence and neonatal mortality rates (NMR) declined in parallel. For the low birthweight neonate, coincident with a precipitous drop in NMR, the CP incidence rate remained essentially unchanged. In the face of increasing neonatal survival, the overall incidence rate of CP declined. The decrease in the absolute risk of CP was limited to the greater than 2,500-g neonatal survivor.