As women progress through their 30s, 40s, and early 50s, their bodies experience a complex and often confusing transformation driven by changing hormone levels. This phase, known as perimenopause, is the precursor to menopause and represents a crucial window of opportunity for understanding how fluctuations in hormones like oestrogen and progesterone, impact not only reproductive health but the entire body.
Many women feel confused or frustrated by the influx of information, often mixed with promises of quick fixes or miracle cures to "balance hormones" and alleviate discomfort. But perimenopause is not something to be 'fixed'—it’s a natural biological transition that, when understood properly, can be navigated with knowledge, self-care, and support.
In this article, we dive into the biochemical shifts that occur during perimenopause and explore how these changes affect multiple systems within the body.
What is Perimenopause?
The word "perimenopause" is derived from two parts:
- "Peri-": This prefix comes from Greek, meaning "around" or "near".
- "Menopause": This term refers to the cessation of menstruation and the end of a woman's reproductive years.
When combined, "perimenopause" means "around menopause." It describes the transitional phase leading up to menopause where the ovaries over time, produce fewer reproductive hormones. It is not a singular moment but a temporary stage that can last up to 10 years, depending on the individual.
During this time, women may notice changes in menstruation such increased irregularity, decreased frequency, changes in cycle length and duration, changes in mood and weight, fluctuations in energy and temperature levels, and even cognitive shifts. With the average age of menopause (whereby a woman has gone 12 consecutive months without menstruation) being between the ages of 47 to 52, this can mean that for some women because perimenopause can begin 2 -10 years prior, they might be in their mid to late 30’s and when they start to notice hormonal fluctuations. Each woman is different and will experience her own unique transition through perimenopause, menopause and into post menopause, some with little to no notable symptoms and others with symptoms that can significantly impact the quality of her life.
There is no test or set of tests to diagnose perimenopause however, according to Canadian Endocrinologist Professor Jerilynn Prior , a midlife woman with regular cycles may be in perimenopause if she notices any three of the nine changes which you can read more about here.
Key Hormones: The Dance of Oestrogen and Progesterone
Understanding the role of key hormones is critical to understanding perimenopause. Oestrogen, progesterone, and testosterone are the primary hormones affected, each with distinct yet interconnected roles within the female body.
Oestrogen: The Regulator of Vital Systems
Estradiol is the main form of circulating oestrogen in women and is often considered the "female hormone" due to its central role in regulating the menstrual cycle and supporting reproductive health. However, its influence extends far beyond reproduction. There are oestrogen receptors in every cell within the female body which are helping to maintain bone density, support cardiovascular function, and regulate mood through its effects on neurotransmitters such as serotonin and dopamine.
What Happens to Oestrogen During Perimenopause?
During perimenopause, circulating oestrogen (estradiol) levels become erratic. The ovaries begin producing less oestrogen, but the decline is not a smooth, linear process. Instead, women experience surges and dips in oestrogen, leading to unpredictable cycles and symptoms. In the perimenopause years there can be up to 10 times the amount of oestrogen present relative to the “reproductive years.”
Progesterone’s primary role is to prepare the uterus for pregnancy and regulate the menstrual cycle. During perimenopause, the production of progesterone drops significantly because ovulation becomes less frequent due to shorter luteal phases and anovulatory cycles despite regular menstruation occurring. This often leads to "oestrogen dominance," a state where the relative balance of oestrogen to progesterone becomes skewed.
Progesterone: The Balancer
Progesterone’s primary role is to prepare the uterus for pregnancy and regulate the menstrual cycle. During perimenopause, the production of progesterone drops significantly because ovulation becomes less frequent due to shorter luteal phases and anovulatory cycles despite regular menstruation occurring. This often leads to "oestrogen dominance," a state where the relative balance of oestrogen to progesterone becomes skewed.
What Happens to Progesterone During Perimenopause?
As progesterone levels decline this leaves oestrogen unopposed, contributing to various symptoms. Progesterone plays a key role in calming the brain by activating GABA receptors, which support relaxation and mood stability. Its mild sedative effect promotes deep, restorative sleep, so when progesterone levels drop, some women say that their sleep can become fragmented and less rejuvenating.
A Whole Systems Approach to Hormonal Wellbeing
It’s important to recognise that hormonal changes do not occur in isolation. Hormones affect every system in the body, and as such, the effects of perimenopause can ripple through multiple systems, from metabolism to emotional wellbeing.
Bone Density
The loss of both oestrogen and testosterone during perimenopause has significant implications for bone density. Women begin losing bone mass in their 30s, but this accelerates during perimenopause. It is estimated that women can lose up to 20% of their bone density in the five to seven years after menopause.
Cardiovascular Protection
Oestrogen acts as a potent vasodilator helping to promote blood flow and maintain vascular health through various mechanisms. Due to the erratic production and eventual decline of circulating oestrogen, women lose the cardio protective effects of oestrogen putting them at greater risk of cardiovascular disease. With heart disease being the leading cause of death the risk increases for women post-menopause.
Mental and Emotional Wellbeing
Neurological symptoms affecting temperature regulation, circadian rhythm and cognitive function can emerge during perimenopause due to the effect that erratic fluctuations in oestrogen and progesterone have on neurotransmitter function within the brain.
Metabolism and Energy Balance
The significant hormonal shifts during perimenopause can impact metabolism and energy balance , leading to slower metabolic rate, increased fat storage particularly around the abdomen and changes in insulin sensitivity.
Why Understanding These Changes Matter
Understanding the natural ebb and flow of hormone levels during perimenopause can be empowering allowing women to navigate this life stage with greater confidence and control, and make informed decisions about her wellbeing.
*The advice in this article is for information only and should not replace medical care. As with any nutritional supplement please consult your qualified healthcare professional before use, especially if pregnant, breastfeeding, if you have a known medical condition or are taking medication. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.