Menstrual and reproductive factors for subarachnoid hemorrhage risk in women: a case-control study in nagoya, Japan.

Background And Purpose: We sought to examine the relationship between menstrual and reproductive factors and the risk of subarachnoid hemorrhage (SAH), using a case-control study.

Methods: Cases consisted of a consecutive series of 124 women patients with first spontaneous SAH aged 30 to 79 years and confirmed aneurysm(s) by angiography and/or CT scan. Hospital and community controls subjects were identified, matched to each case by age (+/-2 years).

Results: Increased SAH risk was associated with (1) earlier age at menarche (adjusted odds ratio [OR]=3.24 for age <13 years compared with age >/=13 years; 95% CI, 1.25 to 4.03) and (2) nulligravidity (adjusted OR=4.23; 95% CI, 1.05 to 7.56). No significant association of SAH risk was found with regularity of menstrual cycle, age at pregnancy, age at first birth, and number of births. The greatest risk was for the combined effect of nulligravidity and earlier menarche (<13 years) (adjusted OR=6.37; 95% CI, 1.12 to 36.2).

Conclusions: The combined effect of several variables related to menstrual and reproductive history may exert a greater influence on risk of SAH compared with a single menstrual or reproductive variable.