SHORT REPORT Febrile convulsions and sudden infant death syndrome

It has been suggested that sudden infant death syndrome (SIDS) and febrile convulsions are related aetiologically. We compared the risk of SIDS in 9877 siblings of children who had had febrile convulsions with that of 20 177 sib-lings of children who had never had febrile convulsions. We found no support for the shared susceptibility hypothesis. It has been suggested that sudden infant death syndrome(SIDS) and febrile convulsions (FC) are relatedaetiologically.1 Both conditions may be age specific reactions to fever in susceptible children, and the common mechanism may be termolabile syncope with cerebral ischaemia.1 The hypothesis is supported by the observations that cats’ reactions to artificially induced fever depend on age; younger kittens tend to die suddenly, older kittens tend to have convulsions, and mature cats tend to remain intact.2 3 Both SIDS and FC occur in time based clusters, and children who die of SIDS are generally younger than children with FC.1 Hyperthermia, which may be caused by infections, heavy wrapping, and prone sleeping,4 5 is a common finding in infants who died of SIDS.6 If the shared susceptibility hypothesis is true, we would expect siblings of children with FC to have an increased risk o