Factors predisposing to a complicated initial febrile convulsion.

131 consecutive admissions to hospital for a first febrile convulsion were studied to find which factors predisposed to a complicated fit--defined as one lasting more than 30 minutes, unilateral, or repeated within the same illness. A significant excess of complicated attacks occurred where the age of onset was less than 16 months, where both family history of convulsive disorder and perinatal abnormality were present, and, in females only, where it was suspected that neurological disorder preceded the first fit.