An incident case-control study of first unprovoked afebrile seizures in children: a population-based study of pre- and perinatal risk factors.

Purpose: The aim of this prospective incident community-based study was to assess the influence of pre- and perinatal risk factors in children in whom an unprovoked afebrile epileptic seizure later developed.

Methods: From November 1, 1985, until June 30, 1987, 75 children aged 0-15 years with a first unprovoked afebrile seizure were identified. After exclusion of cases with neonatal seizures (n = 14), two controls per case were selected from the same province in northern Sweden matched by age and sex. Files from maternity wards and pediatric clinics could be traced for 58 cases and 109 controls. These formed the study group.

Results: In the univariate analysis, the risk for an unprovoked afebrile seizure was significantly elevated for birth order (OR = 9.3; CI, 2.2-39), vaginal bleeding (OR = 17; 95% CI, 3.5-85), onset of hypertension during pregnancy (OR = 4.8; CI, 1.3-17), cesarean section (OR = 18; 95% CI, 3.7-88), short or long gestational age (OR = 6.7; 95% CI, 2.0-22), and an Apgar score < or =6 at any time (OR = 3.8; 95% CI, 1.2-12). None of these six factors was present in 48.3% of the cases and 89% in the controls. A combination of two or more risk factors found to be significant in the univariate analysis showed a pronounced increased risk for seizures (OR = 19; 95% CI, 5.6-65). In the multivariate analysis, the following characteristics remained statistically significant: vaginal bleeding, gestational age, and Cesarean section. Furthermore, smoking also was identified as a risk factor in the multivariate analysis (OR = 3.4; 95% CI, 1.1-10).

Conclusions: Both pre- and perinatal factors may be associated with later development of epileptic seizures in children. However, in many of the cases, no such factors were identified.