High-dose estrogen-progestagen oral contraceptives: a risk factor for aneurysmal subarachnoid hemorrhage?

A 10-year follow-up (1970-79) of a defined general population (n = 159 200) of middle-aged (born in 1911-40), urban, native Swedes, revealed that the prevalence rate of subarachnoid hemorrhage was 2.8 times higher in females than in males. This was mainly due to an accumulation of non-hypertensive aneurysmal subarachnoid bleeds in women born in the period 1932-40. The cases were significantly (P less than 0.001) overrepresented among divorced women, with relative risks of 1.89, 0.98 and 0.63 for divorced women, married women and spinsters (never married), respectively. Since high-dose estrogen-progestagen oral contraceptives have largely been used by the younger members of this study cohort, it may be speculated whether the observed substantial excess prevalence rate of subarachnoid hemorrhage with saccular aneurysm, not reported previously, represents a cohort effect unexpected after the introduction of low-dose oral contraceptives.