Oral contraceptives and stroke

Since 1962, more than 25 studies have been devoted to the relationship between oral contraceptives and stroke. They are all case-control or cohort epidemiological studies and thus contain the difficulties and biases that are inherent in these types of studies. The following conclusions can be drawn from these studies: . High oestrogen content (greater than or equal to 50 mu g) increases the risk of stroke, all stroke subtypes, and stroke death. . Low oestrogen content (<50 mu g) carries a very low or no risk of stroke. . There are no data on progestogen only oral contraceptives. . Stroke risk is greatly increased if associated risk factors are present, in particular hypertension, cigarette smoking and migraine. . Oral contraceptives, even at low doses, significantly increase the risk of cerebral venous thrombosis, which is further enhanced if congenital thrombophilia is present. . The attributable risk of stroke in young women using oral contraceptives is about 1 per 200 000 woman-years. The contraceptive and non-contraceptive benefits of low dose oral contraceptives vastly outweigh their risks provided that other risk factors are absent or well controlled.