Handedness, age at menarche, and age at menopause.

OBJECTIVE

To investigate the relation between handedness and age at menarche or age at menopause, as both handedness and reproductive variables have been suggested to be influenced by the intrauterine endocrine environment.

METHODS

Self-reported information on handedness, age at menarche, age at menopause, and other demographic and reproductive variables was recorded for 10,328 women still menstruating or in natural menopause. These women had been selected as controls in a multicenter case-control study of breast cancer conducted in the 1960s. Left-handedness (including ambidexterity) was modeled as the outcome variable through multiple logistic regression.

RESULTS

After adjusting for center, age, menopausal status, age at menopause, years of schooling, and parity, there was no significant relation of handedness to age at menarche (odds ratio for each year delayed 1.01, 95% confidence interval [CI] 0.97-1.06) or age at menopause (odds ratio 1.00, 95% CI 0.98-1.02).

CONCLUSION

These findings lend no support to the hypothesis that intrauterine endocrine variables associated with handedness also are related to reproductive variables.