Just in case any of you are as unaware as I was...
If you get migraines (real migraines, not just a bad headache... they are different. I've even had migraines less severe than some of my headaches, but they're definitely migraines, it's a totally different expereince), especially the ones with "aura", you shouldn't be taking medications that are oestrogen based (the pill for e.g.). I was surprised and a little scared to find out recently while trying to find a better contraceptive method for me that the WHO consideres the risk of stroke to be unacceptable when you combine the two (it's something like 4 times higher I think). I hadn't known this and have previously been on the pill.
The reason is (as I understand it) that the process of a migraine involves vaso constriction (narrowing of the blood vessels) in the brain (this is what causes the pain and also the visual disturbance in "auras" - partially cutting off blood supply to your visual nerves). This means people with migraine are already at elevated stroke risk. Oestrogen also messes with your blood vessels (either increasing blood pressure or also constricting blood vessels... can't remember which) which, altough considered safe on its own, makes the situation for migraine sufferers worse. If your blood vessels are constricted enough, blood stops getting through and bits of your brain start dying - this is one form of a stroke (the other being when a blood vessel is damaged and the blood leaks into your brain also removing blood supply and causing neural death via removed blood supply and damage from blood being where it shouldn't be, e.g. burst aneurisms).
And you DON'T want to have a stroke.
There are alternatives to the pill, though some of you might have trouble like I do. The mini pill is progestogen based and ok (but you need to be super on time with taking them). The implanon and injection are also ok if they work for you - some people they don't go so well with. And then there's things like IUD's (which you can still have if you haven't had kiddies) and diaphragms. And good ol' condoms of course.
There are benefits and disadvantages to each - go chat with the people at a local family planning clinic, I found them super helpful and they know their stuff about contracteption.