Cerebral palsy (CP) is still the most common cause of chronic motor disability in hildhood. Until now, there has not been any previous national study of the anorama of subtypes, severity or risk factors among children with CP in Norway. his is a population based study of a cohort of children with CP born 1996 to 1998 in orway. These children are recorded in the Cerebral Palsy Register of Norway. The P definition and classification system agreed on by the Surveillance of Cerebral alsy in Europe (SCPE) are applied. The study showed that the prevalence of CP in orway was 2.1 per 1000 live births, comparable with other similar populations.
Most children were classified in the spastic bilateral subtype (49%), about ne third (33%) in the spastic unilateral subtype and less than 10% in the dyskinetic r in the ataxic subtype. Both the distribution of subtypes and gross motor function impairments were comparable with other populations in developed countries. More children in our study had fine motor function impairments, as well as associated impairments. The associated impairments included both impairment of speech and feeding, in addition to impairments of vision, hearing, cognition and presence of active epilepsy.
We identified both breech presentation and induction of labour as independent risk factors for CP. There was a significant increased risk of CP in children born in breech presentation compared to vertex presentation, in particular for singletons born at term by vaginal delivery. Breech presentation was however not associated with specific subtypes of CP or with the extent of gross or fine motor impairments. There was also an increased risk for CP in children after induction of labour. Induction of labour was associated with a higher proportion of children with the bilateral spastic subtype as well as in those born at term with four-limb involvement.
When we studied multiple risk factors (maternal disease, assisted fertilization, plurality, abnormal placental structure, bleeding in pregnancy, small for gestational age, abnormal presentation, Apgar score at 5 minutes <7 and preterm birth) we found that increasing number of risk factors were associated with an exponentially increased risk for CP. Combinations of these risk factors were more common in children born preterm, while both among term and preterm born children, few shared the same combinations of risk factors.