Background: An increased risk of stroke has been found in women with early or late menarche in a cohort in the United Kingdom. It is uncertain if there is a similar increase in risk of stroke in women who experience early or late menarche in the United States.
Methods: Using data from the observational component of the Women’s Health Initiative (WHI) [WHI Observational Study (OS)], we analyzed the 93,676 women aged 50-79 years, who participated in the OS over a period of 12±1 years. We compared the outcome of ischemic stroke in participants of 5 strata of age of menarche (10 years or younger, 11-12 years, 13-14 years, 15-16 years, and 17 years or older), as recorded at the baseline visit. An ordinal regression analysis was run to determine if there was a change in the risk of stroke over these strata.
Results: Of the 93, 676 participants, 6067 reached menarche at 10 years of age or younger, and 965 reached menarche at 17 years of age or older. A smaller proportion of participants who developed an outcome of stroke were 10 years old or younger at menarche as compared to those who never developed stroke (6.4% vs. 6.5% p=0.85). A greater proportion of participants who developed an outcome of stroke were 11-12 years of age at menarche as compared to those who did not develop an outcome of stroke (42.8% vs. 41.3% p <.122). In the ordinal regression, there was a stronger correlation between developing a stroke and being a participant in the categories of 11- 12 years and 13-14 years of age at menarche than in the younger or older age group, respectively (0.14 and 0.103 vs 0.94 and 0.02 p=0.45).
Conclusion: There is no significant increase in stroke risk in senior women in the United States who have menarche at an early (≤10 years) or late (≥17 years) age.