Lack of association between age at menarche and age at menopause: Pró-Saúde Study, Rio de Janeiro, Brazil.

OBJECTIVE

To investigate the association between age at menarche and age at menopause among Brazilian women.

METHODS

This study is based on cross-sectional data obtained in 1999 from technical and administrative employees who were recruited for participation at the Pró-Saúde cohort study in Rio de Janeiro, Brazil. The final study population consisted of 1462 women. Participants completed a self-administered multidimensional questionnaire. In addition to the study exposure (age at menarche) and outcome (age at menopause) variables, the following independent variables were selected: parity; schooling; self-classified race; use of oral contraceptives; smoking; and body mass index (BMI). Median ages at natural menopause and the survival curves were estimated by the Kaplan-Meier method. To estimate the association between age at menarche and age at natural menopause, a Cox semi-parametric model was fitted. Women who were still menstruating, who had undergone surgery for the removal of the uterus or ovaries, or who were in perimenopause were censored.

RESULTS

Natural menopause occurred in 205 women. The median and mode for natural menopause were 51.7 and 50 years of age, respectively. In the multivariate analysis, no statistically significant association was observed between age at menarche and age at menopause (HR: 1.01; 95% CI: 0.93-1.11).

CONCLUSION

In the current study, the hypothesis of an association between age at menarche and age at natural menopause was not confirmed. Specific studies on the determinants of age at menopause should be conducted, due to the importance of menopause in the causality of diseases with high case mortality rate.