Seasonality of birth in epilepsy: a Danish study.

OBJECTIVES

A recent British epidemiological study, having found that the seasonality of birth in a large epileptic sample was significantly different from that of the general population, has pointed to neurodevelopmental disruption as the likely mechanism to cause at least part of the epilepsies of unknown aetiology. The aim of this study is to replicate the British study using a large Danish sample.

MATERIAL AND METHODS

The population studied is composed by all the 50,886 patients discharged from Danish Hospitals, with a diagnosis of epilepsy, in the period from 1977 to 1993. The seasonal pattern of birth in this sample has been compared, using regression methods, with all the live births in Denmark.

RESULTS

The results were strikingly similar to the British study, with a deficit of epileptic births in September and an excess during the winter months.

CONCLUSION

This study seems to confirm the seasonal presence in the environment of an aetiological factor(s) for epilepsy which acts in the perinatal period disrupting the neurodevelopment.