The Biodemographic Models of Reproductive Aging (BIMORA) Project: Methods and Steroid Hormone and Menstrual Cycle Findings in a Five Year Prospective of the Transition to Menopause

Rebecca J. Ferrell, Georgetown University
Kathleen A. O'Connor, University of Washington
Darryl J. Holman, University of Washington
Eleanor Brindle, University of Washington
Rebecca C. Miller, University of Washington
Deborah E. Schechter, University of Washington
Tristan Gorrindo, Georgetown University
Lauren Korshalla, Georgetown University
James Simon, Women's Health Research Center and George Washington University
Ann Voda, University of Utah
James W. Wood, Pennsylvania State University
Phyllis Kernoff Mansfield, Pennsylvania State University
Maxine Weinstein, Georgetown University

Endocrinological and menstrual cycle changes during the menopausal transition have been studied in cross-sectional and longitudinal studies. Sample size and study length limitations complicate the interpretation of these data. We describe recruitment, sampling and collection methods, and present analyses of menstrual cycle and steroid hormone data, for a five-year, prospective study of the menopausal transition. Women (n=156, ages 25-60 years), for whom prospectively collected menstrual and health data for up to thirty years were also available through the TREMIN Trust, collected daily urine specimens and bleed data for six months in each of five consecutive years. Average collection period per woman was 21 months, totaling 3,289 woman-months of data. Average year-to-year subject retention was ninety percent; twenty-five subjects definitively made the transition to non-menstruating status. Women ages 40-55 had highly variable steroid levels and cycle lengths, including the maximum observed steroid values and the shortest observed cycles in the sample.