Cerebral palsy in two national cohort studies.

The prevalence of cerebral palsy in the 1958 British Perinatal Mortality Survey and the 1970 British Births Survey remained constant at 2.5/1000 births (40 and 41 cases, respectively). The prevalence at 10 years was higher in the 1970 cohort in which all children with cerebral palsy survived, whereas 22% of the cases in the 1958 cohort died during the first 10 years of life. A case-control study matched three controls for social class, maternal age, parity and marital state, and a further three controls for the infant's sex, gestation, and birth weight. Comparison of cases and controls showed no consistent differences in social and environmental factors, history of pregnancy, labour, or delivery. Important differences were found in the incidence of respiratory and neurological symptoms in the neonatal period. These prospective data derived form two whole populations of births support the hypothesis that most cases of cerebral palsy are not associated with adverse obstetric factors, and confirm that neonatal neurological symptoms are associated with subsequent cerebral palsy.