Background It is well known that cerebral aneurysms occur more frequently in women, with numerous studies suggesting a role for hormones in aneurysm pathogenesis. Estrogen promotes normal physiologic vascular endothelial function but also fluctuates during the menstrual cycle and drops significantly at menopause.

Methods A retrospective, case control study was conducted to determine if exogenous estrogen use, which stabilizes estradiol levels, had any association with the presence of cerebral aneurysms. 60 women with intradural cerebral aneurysms were interviewed about their basic medical and female reproductive health histories, including oral contraceptive pill and hormone replacement therapy use and duration of use. This information was compared with the same data collected from women in the general public, as represented by 4682 women contacted through random digit phone dialing in the National Institute of Child Health and Human Development sponsored Contraceptive and Reproductive Experiences Study, published in 2002.

Results Multivariate logistic regression showed a significant association between a lower rate of oral contraceptive (OR 2.1, CI 1.17 to 3.81; p=0.01) and hormone replacement therapy (OR 3.09, CI 1.54 to 6.22; p=0.002) use and the presence of a cerebral aneurysm.

Conclusion These data suggest that exposure to exogenous estrogen agents in women is associated with a lower frequency of cerebral aneurysms.