Monday, March 17
Tom Vogl: Differential Fertility, Human Capital, & Development
Lisabeth, L.D., Sioban D. Harlow, B. Gillespie, X.H. Lin, and M.F. Sowers. 2004. "Staging Reproductive Aging: a Comparison of Proposed Bleeding Criteria for the Menopausal Transition." Menopause-the Journal of the North American Menopause Society, 11(2): 186-197.
Objective: A staging system for female reproductive aging has recently been proposed. Bleeding criteria are an important component of a staging system, as bleeding patterns are readily observable. Several different bleeding criteria have been proposed, but their concordance and validity have not been evaluated. Five proposed bleeding criteria or markers for the onset of early menopausal transition and four criteria for the onset of the late transition were evaluated using data from the Menstruation and Reproductive History Study, or Tremin Trust. Design: Correlations between time from age 35 to each marker event were assessed using Kendall's tau correlation coefficients. Kaplan-Meier survival analysis was used to examine associations between the marker events and age at final menstrual period (FMP). Results: The first occurrence of marker events for the late menopausal transition demonstrated low to high correlation (r = 0.23 to 0.77), whereas the first occurrence of marker events for the early transition stage demonstrated no correlation to moderate correlation (r = 0.0 to 0.65). After age 40, the occurrence of the marker events distinguished a subgroup of women who were more proximate to their FMP. Differences in years to FMP between women with and without the marker events were greatest in the early to mid-40s and declined with age. Conclusions: A 60-day cycle may be a desirable marker for entry into the late transition stage because of its reliability, proximity to the FMP, and ease of calculation. More work is needed to conceptually define the onset of the early menopausal transition before appropriate bleeding criteria can be established.