Epidemiology
CP is the most common cause of childhood disability in Western societies. The incidence is 2-2.5/1000 live births. Some affected children do not survive and the prevalence varies between 1-5/1000 babies in different countries. It was previously thought that improvements in perinatal and

obstetric care would decrease the incidence of CP. However, the incidence has not declined and the overall prevalence increased during the 1980s and 1990s. This is explained by increased survival of premature and very-low-birth-weight infants and by a rise in the number of multiple births. Even at centers where optimal conditions exist for perinatal care and birth asphyxia is relatively uncommon, the incidence of CP in term babies has remained the same. This has led researchers to consider unknown prenatal causative factors.

Etiology
The etiology can be identified only in 50% of the cases. Certain factors in the history of the child increase the risk of CP. The incidence of CP among babies who have one or more of these risk factors is higher than among the normal
population. The clinician should therefore be alerted to the possibility of the presence of CP in a patient with these factors.