The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


The timing of the onset and duration of perimenopause in baboons and humans

KATHLEEN A. O'CONNOR1,2, NICOLA NERETTI3, ANNE BRONIKOWSKI4, DARRYL J. HOLMAN1,2 and MARC TATAR5.

1Anthropology, University of Washinton, 2Center for Studies in Demography and Ecology, University of Washington, 3Molecular Biology, Cell Biology, and Biochemistry, Brown University, 4Ecology, Evolution and Organismal Biology, Iowa State University, 5Ecology and Evolutionary Biology, Brown University

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Several species of non-human primates show evidence of reproductive aging and menopause, indicating that the mechanisms underlying reproductive senescence are conserved in the primate lineage. The perimenopause is defined by the onset of irregular ovarian cycles and signifies aging of the reproductive axis, but little is known of the timing of this process in either human or non-human primates. We tested the hypothesis that the timing of this aging process is similar in baboons (non-seasonal breeders) and humans.

We used a Bayesian change-point analysis with longitudinal data on menstrual cycle lengths to identify the onset of irregular cycling, and length of time from this onset to menopause. Cycle lengths were calculated using prospectively recorded menstrual bleeds from 1) 41 captive baboons at the Texas Biomedical Research Institute for which we could confidently establish ages of perimenopause and menopause, and 2) up to 440 women born prior to 1939 who kept menstrual calendar cards for as long as 30 years as part of the TREMIN TRUST research program.

For the baboons we found that the time between a distinct change in cycle regularity and menopause was effectively a fixed quantity regardless of the age of perimenopause onset, and this duration of perimenopause is 4.5 years. Analyses of the TREMIN data are in progress. While there is wide individual level variation in the age at menopause, the duration of reproductive senescence leading up to the menopause is comparatively invariant.

Grant sponsors: NICHD, R24 HD42828; NIA, R01 AG030329.

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