Epidemiology of infantile hydrocephalus in Sweden. I. Birth prevalence and general data.

The livebirth prevalence of infantile simple hydrocephalus (IH) was investigated in a Swedish population-based survey. The study comprised all liveborn infants with IH apparent before the age of one year and born in the study area between 1967-82. A total of 202 infants fulfilled these criteria; of these, 141 (70%) were born at term and 61 (30%) were preterm. The mean prevalence was 0.53 per 1,000, with a slightly increasing trend from 0.48 in 1967-70 to 0.63 in 1979-82. The increase was entirely referable to the preterm group, in which the prevalence rose from 0.13 per 1,000 in 1967-70 to 0.30 in 1979-82. There was no tendency to an increase in the term group. In 12 of 23 children born very preterm the origin of the IH was a diagnosed cerebral haemorrhage. This is compatible with the increased risk of the latter condition that has been found in very preterm newborns. The mortality among children with IH was highest before the age of one year (15%), after which it was 1.2% per year.