Determinants of age at menopause in women attending menopause clinics in Italy

OBJECTIVE: We analysed the mean age at menopause and its determinants in 31,000 women attending menopause clinics in Italy. DESIGN: Between 1997 and 2003 we conducted a large cross-sectional study on the characteristics of peri- and post-menopausal women attending a network of first-level outpatient menopause clinics in Italy for general counseling or treatment of menopausal symptoms. Spontaneous menopause was defined as natural cessation of menses for 12 or more months. A total of 31,834 women with spontaneous menopause entered the study. RESULTS: The mean age at spontaneous menopause was 51.2. The age at menopause did not markedly changed with cohort of birth. Higher education was associated with lower age at menopause (51.1 in women with low education versus 51.3 for women with high school or university degree, p<0.05). A higher body mass index (BMI) was associated with later age at menopause. Smokers reported a lower age at menopause (51.2 in nonsmokers versus 51.1 in smokers, p<0.05). A later age at menarche was associated with a later age at menopause. Likewise, lifelong irregular menstrual cycles and higher parity were related with later age at menopause. No association emerged between ever oral contraceptive use and age at menopause. CONCLUSIONS: Low educational level, lower BMI, smoking, early menarche, nulliparity and regular cycles are independently associated with lower age at natural menopause in a large sample of women attending menopause clinics in Italy. However, in absolute terms the effect of these factors in our sample is very small.