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This is significant because for many
women, including the growing number who choose to start
families later in life, predicting their biological
clock's relation to the timing of their menopause and
infertility is critically important.
Professor MaryFran Sowers from from the
Department of Epidemiology says the information provides
a roadmap as to how fast women are progressing through
the different elements of their reproductive life and
could change the way women behave.
A research team led by Sowers examined
the naturally occurring changes in three different
biomarkers over the reproductive life of more than 600
women:- follicle-stimulating hormone (FSH), anti-Mullerian
hormone (AMH) and inhibin B.
They discovered that the biomarker AMH
declined to a very low or non-measurable level five
years prior to the final menstrual period, a decline
which signals a critical stage in which a woman probably
has so few follicles (eggs) that her fertility becomes
increasingly questionable.
Professor Sowers says the changes in
AMH and inhibin B concentrations were found to be
predictive of the time to menopause.
The research team also measured and
reported the rates of change in FSH and used the
information to identify different reproductive stages.
Based on a woman's age and the level
of FSH in the blood, the researchers were able to
describe four different stages that occur for women from
their late reproductive period to the time of their
final menstrual period.
While it is now possible for doctors
to measure hormones, information about AMH, inhibin B or
FSH collected on a large group of women over time has
not been available in order to relate changes in the
levels to fertility or to a menopause endpoint.
Professor Sowers says people want
information about how long they will remain fertile and
when they are likely to have their final menstrual
period.
Professor Sowers says now it may be
possible to use specific FSH levels combined with age,
to reveal the current reproductive stage.
Sowers says there are now numbers,
from enough women, evaluated over a long time period, to
describe the reproductive aging process which will give
women and clinicians an expanded way to look at menses
and endocrine events in terms of reproductive
progression.
Sowers said additional study results
have been submitted to describe the amount of bone loss
that occurs at the different FSH stages, so if women and
clinicians know where women are in the various
reproductive stages, it will further their understanding
of the likely health implications associated with each
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