Very preterm children are at increased risk of reduced processing speed at 5 years of age, predicted by typical complications of prematurity and prenatal smoking.

Very little is known about risk predictors for the development of reduced processing speed, which can cause intellectual problems in later life. This study identified risk predictors at 5 years of age in a population-based cohort of very preterm infants.Between January 2003 and August 2006, all preterm infants born before 32 weeks of gestation in Tyrol were prospectively enrolled (n = 223), and 161 underwent a detailed examination at 5 years of age, including a cognitive assessment using the Wechsler Preschool and Primary Scale of Intelligence, third edition. The processing speed quotient is calculated on the basis of two subtests that assess symbol search and coding. The association between prenatal and postnatal factors and reduced processing speed was analysed by means of logistic regression analysis.Of 161 children tested, 55 (34.2%) showed reduced processing speed. In 55.6% (n = 30) of these children, reduced processing speed was related to full-scale intelligence quotient scores of <85. Smoking in pregnancy, steroids for chronic lung disease and intracerebral haemorrhage predicted reduced processing speed at 5 years of age.More than a third of the very preterm children we tested showed reduced processing speed at 5 years of age, and predictors were typical complications of prematurity and smoking in pregnancy.