Menstrual cyclicity and the pre-menopause.

The phase of menstrual life in which transition occurs from relatively regular cycles to the termination defined as menopause is studied for several hundred women who have kept accurate records of their menstrual flows. Age at both natural and oestrogenic menopause, age upon entry into the menopausal transition, and duration of that transition are analysed quantitatively. Detection of entry into the pre-menopausal phase is discussed. A complication of reactions to climacteric discomforts as recorded voluntarily by the study participants is presented.