Determinants of age at menopause in Italy: results from a large cross-sectional study. ICARUS Study Group. Italian Climacteric Research Group Study.

OBJECTIVE: To identify the determinants of age at menopause in an Italian population, using data from the Italian Climacteric Research Group Study (ICARUS). METHODS: ICARUS is a prospective study of the effect of menopause on women's health that has been running in menopause clinics throughout Italy since 1995. A total of 4300 women with spontaneous menopause, aged 55 years or more and observed for the first time at the participating centres are included in the present analysis. RESULTS: The mean age at menopause in the total population was 50.9 years. After taking into account potential covariates, the women reported smoking, had a slightly lower mean age at menopause than non smokers 50.4 versus 50.9 years; P = 0.01. The mean age at menopause in nulliparae was 50.0 years, and, respectively 50.4, 50.6, 50.9, 51.2 and 50.9 years in those reporting 1, 2, 3, 4 and 5 or more births (P < 0.01). A low body mass index and an early age at menarche were associated with early menopause in the crude analysis, but these associations disappeared after taking into account the confounding factors. CONCLUSIONS: This study offers an estimate of the mean age at menopause of women attending menopause clinics in Italy, on the basis of the data obtained from a large sample. It also indicates that smoking and nulliparity are associated with early menopause.