Continuing decline in the prevalence of cerebral palsy in Denmark for birth years 2008-2013

Aim: To quantify and analyse the prevalence and clinical features of cerebral palsy (CP) in Denmark for birth years 2008-2013 and compare results with previous periods.

Method: A nationwide register-based study covering all children with a confirmed diagnosis of CP born in Denmark. Information about CP subtype, aetiology and severity was collected from the Cerebral Palsy Follow-up Program and supplemented from medical files. Data from the Danish Medical Birth Register was included, and the results were compared to previous data from the Danish National Cerebral Palsy Register. Prevalence per 1000 live births and proportions were analysed using the Cochran-Armitage test for trend.

Results: The period covered 368,618 live births and 636 children with CP, making the overall prevalence for the period 1.73 per 1000 live births. This was significantly lower than the prevalence of 1.99 for the previous period 1999-2007 (p = 0.004). The decline in prevalence between the two periods was mainly due to a decrease in children with bilateral spastic and dyskinetic CP born after 37 gestational weeks. The decline in prevalence was accompanied by a smaller proportion of children with associated impairment.

Conclusion: We found a decrease in prevalence and severity in CP among Danish children. The decline was most pronounced in children born after 37 gestational weeks with severe subtypes of CP. National guidelines that recommend induction of labour before the completion of week 42 and therapeutic hypothermia for term neonates with hypoxic-ischaemic encephalopathy, may have contributed to the decline.