There are different risk factors which make a person more likely to have migraines. Being a female is a risk factor, and so is having family members who had migraines. For a person who has migraines, there are different trigger factors which may set off a migraine attack. In a large group of females who have migraines, one of the main trigger factors is when the amount of the hormone estrogen in their body either drops too low or "fluctuates" (goes up and down).