Infantile hydrocephalus in preterm, low-birth-weight infants--a nationwide Swedish cohort study 1979-1988.

All Swedish infants with shunt-treated infantile hydrocephalus, born during the period 1979-88 at < or = 34 weeks gestational age and of low birth weight, were studied. Ninety-six infants were born before 32 weeks and 50 at 32-34 weeks. The mean gestational age in the very preterm group gradually decreased from 29.5 to 27.3 weeks. The mean live birth prevalence was 15.9 per 1000 very preterm infants, and 5.1 per 1000 moderately preterm infants. No significant secular prevalence trends were found. The perinatal mortality decreased successively. The slowly decreasing trend in moderately preterm infants may imply better outcome in survivors. The slightly increasing trend in very preterm infants could be explained by more survivors in the low gestational age group. The aetiology was considered perinatal in 94% of the very preterm group and in 56% of the moderately preterm group; prenatal in 1% and 32% of infants, respectively. Additional neuro-impairments were present in 82% of infants, cerebral palsy being the commonest (74%).