Rates of cerebral palsy in Victoria, Australia, 1970 to 2004: has there been a change?

AIM: The aim of this study was to assess overall and gestational age-specific trends in the rate of cerebral palsy (CP) in Victoria, Australia, and to compare these findings with other population data. METHOD: Individuals born in Victoria from 1970 to 2004 with non-postneonatally acquired CP were identified from a population register; 3491 were included in the study (1963 males, 1528 females). After a literature review, comparison data were extracted from publications using previously devised inclusion criteria. Rates were calculated per 1000 live births for all CP and by gestational age group: these were tabulated and plotted by year of birth. RESULTS: Data from nine registries, including the Victorian register, showed an increase in the rates of CP over the 1970s and 1980s, consistently seen in extremely preterm (<28 wks) survivors but also in those born at term (≥37 wks). Since the early 1990s, CP rates either stabilized or decreased, particularly for children born extremely preterm. INTERPRETATION: Increases in the rates of CP during the 1970s and 1980s are in part because of the increasing survival of extremely preterm infants that occurred without a concomitant improvement in neurological outcomes. Evidence from population samples now suggests that this trend has been reversed since the mid- to late 1990s.