Menopause 101

Estrogen is important because it is a master regulator of metabolism, brain health, cell division, bone strength, and many other functions in addition to reproduction.[15][16]

Estrogen is a steroid hormone (also called estradiol or E2) secreted by the ovaries and adipose tissue and its’ secretion becomes irregular as early as the Late Reproductive Stage (LRS)  (Reproductive: Late Stage) of life. [13] Estrogen may make very dramatic oscillations during the menopausal transition stage, finally steeply declining to close to zero in the last year before menopause. How estrogen variability directly affects short-term symptoms like mood and hot flashes, or chronic conditions like bone thinning (osteopenia and osteoporosis), is not understood.  [14]

Progesterone is a steroid hormone, secreted by ovaries with more specialized and fewer known functions than estrogen.[17] Levels of progesterone gradually decrease over the menopause transition before stabilizing at low levels after menopause. [18] [19]

Progesterone mainly functions in fertility and pregnancy. It is secreted by the corpus luteum body of the ovary, triggering changes in the uterus that make it ready to support an implanted fertilized egg. The human placenta also secretes progesterone in support of pregnancy. As well, progesterone is involved in regulating breast tissue growth and differentiation, along with estrogen.

Progesterone may reduce the stiffness of blood vessels, reduce water retention in the body, and modulate the sleep regulating hormone melatonin. [20] Consequently, the gradual loss of progesterone during menopausal transition may increase water retention and affect sleep quality.

During the late reproductive stage (Reproductive: Late Stage), follicle stimulating hormone (FSH), oscillates in sync with your other reproductive hormones. FSH triggers oocyte (egg cell) maturation and release and stimulates the secretion of estrogen from the ovary.

During the early menopausal transition (Reproductive: Early & Peak Stage) , FSH rises steeply to high levels.  FSH levels plateau near the end of the menopausal transition and persists at this level post-menopause. [22][23][24] High levels of FSH, along with declining estrogen, may affect bone health and increase the likelihood of obesity. [25]

Blood glucose levels may become dysregulated and variable during menopausal transition, possibly due to irregular and declining estrogen and rising FSH. Brain glucose dysregulation may contribute to memory and concentration challenges seen during the menopause transition. [26]

MYTH

This myth is rooted in ageist and sexist attitudes. Most women in menopausal transition are healthy, happy and productive. Women cope with their symptoms like they cope with most other challenges in life – adequately at worst and successfully at best.

MYSTERY

Generally estrogen and progesterone levels decline and FHS (follicle-stimulating hormone) levels increase, all stabilizing at new levels following menopause. Changes in hormone levels are highly variable from woman to woman, and currently there is little data (and no easy way to collect data) about the individual woman’s reproductive hormone levels on a day-to-day, and month-to month, basis during menopausal transition. Other important hormones and neurotransmitter levels are not known either.[27]

MYSTERY

Since hormone levels can’t be accurately tracked day-to-day/ month-to-month for individual women, the impact of hormones on symptoms is speculative for most symptoms. Technological tracking of symptoms and biomarkers over time is lacking. The result is that current research can only correlate changing hormones with symptoms for averaged populations of women, and with only a rough idea of timing of these events.

MYSTERY

There aren’t solid answers but the ideas from anthropology, genetics and evolution give some interesting hypotheses. Here are two of them:

1 “Why do women outlive their fertility?”

Twenty-first century women (and people in general) are living 40- 50 years longer than women did before 1900. At that time, most women died around age 40 (across different cultures), before even reaching the menopausal transition. Living through the menopausal transition and beyond is relatively recent. 

There may be no evolutionary “purpose”, or survival advantage, to either individual women or to their descendants. The length of the reproductive life span in human females is comparable to other great apes, however great apes die soon after their reproductive systems age and stop functioning. The hypothesis is that menopause might not be the key trait. Perhaps the ability to extend life post-menopause is the critical trait that needs more attention. [28] 

2 “The Grandmother Hypothesis”

Overwhelmingly, women of past generations had children at a younger age than now, typically starting in their teens and early 20’s. After children are born to a young woman and her family, her genetic contribution to future generations is complete. Since childhood disease and trauma impact human mortality so strongly, children’s survival becomes evolutionarily paramount. When women have children that survive long enough to bear them grandchildren, the continuation of the woman’s genes becomes more probable. As well, grandmothers may improve the likelihood of her grandchildren’s survival by sharing her resources, help and knowledge, creating more insurance for the survival of her genes. This hypothesis is called “Kin Selection” and it proposes that there are strong natural selection factors supporting longer lifespans (for both women and men). [29][30]