We conducted a matched case-control study to identify risk factors for
first febrile seizures, with special emphasis on characteristics of t
he acute illness episode. Cases were identified through hospital emerg
ency departments; controls were identified through outpatient clinics
and emergency departments. Sixty-nine children with first febrile seiz
ures and no history of previous unprovoked seizures were matched for a
ge (+/-6 months), site of routine pediatric care, and date of visit (/-2 weeks) with 1 or 2 febrile controls who had no history of previous
febrile or unprovoked seizures, Medical records for the index visit w
ere reviewed, and parents were interviewed by telephone. Illness chara
cteristics examined included height of temperature, type of underlying
illness, contact with a physician during the illness but before the i
ndex visit, and use of acetaminophen or decongestants. Family history
of febrile and of unprovoked seizures, sociodemographic characteristic
s, daycare use, and selected pre- and perinatal variables were also st
udied. On multivariable analysis, significant independent risk factors
were height of temperature, history of febrile seizures in a first- o
r in a higher degree relative. Gastroenteritis as the underlying illne
ss had a significant inverse (i.e., protective) association with febri
le seizures. Maternal smoking during pregnancy was a marginally signif
icant predictor of febrile seizures.