Staging the menopausal transition: data from the TREMIN Research Program on Women's Health.

The present study was conducted to test the assumptions of a staging system of reproductive aging that was proposed at the Stages of Reproductive Aging Workshop (STRAW) in 2001. Using longitudinal data provided by 100 women over a period of 3-12 years, we asked whether midlife women move in a uniform progression from pre- to peri- to postmenopause, as refuted by earlier studies but proposed by the STRAW model, or whether they differ from this assumed pattern. Participants were recruited from the TREMIN Research Program on Women's Health, the oldest ongoing study of menstruation and women's health in the world. Eligibility criteria included reaching menopause during the course of the study and not using exogenous hormones. Participants provided annual self-reports of menopausal stage based on observations of their menstrual cycles ("regular," "changing," and "menopausal"). Findings revealed a lack of uniformity as women progressed toward menopause. From 8 to over 20 different perimenopausal stage patterns were observed, depending on the analysis. While the most common pattern was to progress from regular to changing to menopause, some women experienced menstrual bleeding after a year or more of amenorrhea, others flip-flopped between stages, and still others skipped directly from regular bleeding to menopause. We conclude that there is considerable variation in women's movement across menopausal status categories and urge researchers to accommodate such findings in their model building.