Correlates of age at natural menopause in the cohorts of EPIC-Italy.

A large number of studies have investigated the factors correlated to age at natural menopause in several populations. However, information on genetics and life-style factors influencing the age of onset of menopause in different populations is of current scientific interest. Specifically, for Italian women there are no large population-based data. The EPIC-Italy collaboration is a source of data of this kind; moreover, the geographical distribution of the cohorts (recruited in northern, central and southern Italy) is an added value as regards the scientific interest of these data. A number of biological and life-style-related factors have been analyzed to evaluate their association to the age at natural menopause in 14,454 menopausal women of the EPIC-Italy collaboration. As regards life-style and environmental factors, the main results are: a) women living in different areas of the country have different ages of onset of natural menopause; b) educational level is significantly associated to this age and may explain part of the between-center difference; c) cigarette smoking appears as a major correlate and probably determinant of the age at natural menopause across all the Italian cohorts; d) alcohol consumption does not have any relationship with the age at natural menopause; e) the use of oral contraceptives may influence age at natural menopause. As regards biological factors, short cycles and low parity have been found associated with earlier menopause. Overall, the results concerning menstrual cycles, parity, and cigarette smoking are consistent with the hypothesis that the number of oocytes in the ovary is pre-determined and any acceleration or impairment of the ovarian function leads to reduce the duration of the reproductive life.