Relationships between Age at Menarche and Risk of Cardiovascular Disease Mortality among Japanese Women: The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC) Study

Aim: In this study, we aimed to evaluate the association between age at menarche and risk of cardiovascular disease mortality. Methods: In total, 54,937 women aged 40–79 years old between 1988 and 1990 without a history of cardiovascular disease were eligible for analysis and were followed through December 2009. We used the Cox proportional hazards models to examine the association between age at menarche and risk of cardiovascular disease. Results: Compared with women with age at menarche of 15 years, the hazard ratios (95% confidence intervals) of stroke were 1.22 (0.85–1.75) for women with age at menarche of 9–12 years, 1.08 (0.85–1.36) for those of 13 years, 1.23 (1.02–1.47) for those of 14 years, 1.27 (1.07–1.50) for those of 16 years, 1.16 (0.95–1.41) for those of 17 years, and 1.39(1.16–1.68) for those of 18–20 years (P for trend=0.045). A similar pattern was observed for hemorrhagic stroke, ischemic stroke, and total cardiovascular disease. No such association was found for coronary heart disease. When stratified by age, for women aged 40–59 at baseline, the similar U-shaped association was observed. In contrast, for women aged 60–79 years at baseline, a significantly high hazard ratio was noted in the group of late age at menarche, but not in the group of early age at menarche. Conclusions: Both women with early and late age at menarche were determined to have higher risk of death from stroke and cardiovascular disease.