I am going to speak for my girlfriend here. She asked her doctor this same question, and she was a cigarette smoker as well. Her doctor very seriously told her to stop smoking cigarettes while on birth control (didnt help at the time unfortunetly, but I have since nagged her enough that she quit months ago), but when the subject of marijuana came up, her doctor essentially told her that there are many other reasons to not smoke weed, but that is not specifically one of them. My gf has a history of migraines and stress headaches and cannabis is still the only drug that immediatly gets rid of it, her doctor doesnt neccessarily promote it but does support it.