Some scientists believe that fluctuating levels of hormones are closely linked to the cause of migraines.
Some women who experience migraines say they are more likely to have an attack around the time of their period. This is known as a menstrual migraine. Just before women have their period, levels of the hormone oestrogen fall.
Women can have menstrual migraines from two days before to three days after the first day of their period. About 1 in 7 women who have migraines only have an attack around the time of their period. This is known as a pure menstrual migraine. Around 6 in 10 women with migraines have attacks at other times too.