The incidence and risk factors of epilepsy in children born preterm: A nationwide register study

Objectives: The aim was to compare the incidence of epilepsy between very preterm (VP) ( < 32(+0) weeks), moderately preterm (MP) (32(+0) -33(+6) weeks), late preterm (LP) (34(+0) -36(+6) weeks) and term infants (>= 37 weeks) and to establish and compare risk factors of epilepsy in these groups. Methods: The national register study included all live born infants in Finland in 1991-2008. Excluding infants with missing gestational age, a total of 1,033,349 infants were included in the analysis and they were analyzed in four subgroups (VP, MP, LP and term) and three time periods (1991-1995, 1996-2001 and 2002-2008). Results: 5611 (0.54%) children with epilepsy were diagnosed. The incidence of epilepsy was 2.53% in the VP, 1.08% in the MP, 0.75% in the LP and 0.51% in the term group. Intracranial hemorrhage (OR 3.48; 95% CI 2.47-4.89) and convulsions in the neonatal period (OR 13.4; 95% CI 10.2-17.6) were associated with an increased risk of epilepsy. Compared to the term group, preterm birth (VP OR 4.59; 95% CI 3.79-5.57, MP 1.97; 1.48-2.63, LP 1.44; 1.25-1.68) was associated with an increased risk of epilepsy after adjusting for maternal, pregnancy, delivery and sex variables. Conclusions: The incidence of epilepsy decreased by advancing gestational age at birth and preterm birth predicted an increased risk of epilepsy in childhood. Intracranial hemorrhage and neonatal convulsions were strongly associated with an increased risk of epilepsy.