My wife is on birth control levora (ethinyl estradiol and levonorgestrel). every month when she finishes the pills she gets these terrible migraines and bp rises. why is this??

Side effects: Those symptoms are listed as possible side effects and are not good. Definitely consult w/ the doctor about alternatives ASAP. Reasons are not as important as avoidance - but they can be easily declared as hormonal imbalances resulting from their artificial manipulation. There are other good birth control choices - seek one and then you both will be healthier and happier.