Catamenial seizures are seizures that occur in relation to a womans menstrual cycle. It is surmised that the elevation of estrogen levels may leave a woman more prone to seizures during certain stages of the cycle.

The times during the cycle when the seizures are most or least active seems to depend upon the type of seizure the woman is prone to.

In a woman with absence seizures, seizures most often occur between day 16 and day 28 of the average cycle, and the fewest seizures occur during menstruation. however in women who suffer partial seizures, more seizures are experienced during ovulation and menstruation and less during day 16 - 28.