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August 16, 2026
Sharon Burbat
Menopause unfolds differently for every woman. What happens during premenopause, perimenopause, menopause, and postmenopause — and how the body changes along the way.
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The menopause is often reduced to hot flashes and the end of menstruation. In reality, the hormonal transition usually begins years before the last menstrual period and is far less straightforward than the term implies. Hormones fluctuate, the cycle shifts, and symptoms can come and go. Some women barely notice any of this, while others experience this time as a profound physical and emotional turning point.
Medically, the years surrounding the last menstrual period are defined more precisely. Four phases of menopause are commonly referenced: premenopause, perimenopause, menopause, and postmenopause. This framework is useful, though not quite as clear-cut as it might initially sound. Strictly speaking, menopause is not a phase but a single moment in time: the last spontaneous menstrual period. And the transitions before and after it cannot be tied to a specific age.
In simplified terms, the progression looks like this:
When these stages begin — and how they make themselves felt — cannot be tied to a specific age.
Premenopause is where the first conceptual difficulty arises. In everyday usage, it is often understood as the first phase of menopause. Medically, however, "premenopausal" primarily refers to the time before menopause. The internationally used STRAW+10 classification therefore draws a clearer distinction between the reproductive phase and the actual menopausal transition.
Long before the last menstrual period approaches, the ovarian reserve begins to change: the number and quality of follicles decrease with age. The menstrual cycle may initially remain regular, yet certain hormone levels shift — without this necessarily meaning that a woman is "in menopause."
In practice, the distinction from the next phase is particularly important: when the previously familiar cycle becomes increasingly irregular, the actual menopausal transition has begun.
For many women, perimenopause is what they think of as menopause in everyday life. It encompasses the actual transition to menopause and the first twelve months after the last menstrual period.
Hormonally, this period is more complex than the common idea that estrogen levels simply decline slowly and steadily. In fact, levels can fluctuate considerably during perimenopause. The number of follicles continues to decrease, ovulation becomes more irregular, and cycles without ovulation grow more frequent.
This also affects progesterone production. At the same time, estrogen levels can still spike temporarily before dropping sharply. Only as the process continues does the overall decline in estrogen production gain the upper hand.
This dynamic explains why symptoms don't necessarily worsen in a steady, predictable way. A woman may feel perfectly well for several weeks or months, then suddenly find herself dealing with sleep problems or hot flashes again.
One of the most telling signs of perimenopause is not a single lab value, but the menstrual cycle itself. In the early transition phase, cycle length becomes increasingly variable. Later, gaps of 60 days or more between periods may occur. Bleeding can become heavier or lighter and vary in duration.
That said, not every unusual bleed is automatically attributable to menopause. Very heavy, unusual, or newly occurring bleeding irregularities should be evaluated by a gynecologist.
The best-known symptoms are hot flashes and night sweats, medically referred to as vasomotor symptoms. These can occur even while a woman is still getting her period regularly or at least occasionally. Sleep disturbances are also common.
Psychological changes can also play a role during this phase. Some women report increased irritability, mood swings, anxiety, or low mood. Difficulties with concentration and memory — often described as "brain fog" — are frequently mentioned as well. Headaches and joint discomfort may also occur, among other symptoms.
Due to the changing effects of estrogen, vaginal dryness and shifts in sexuality can already appear during this phase.
How intensely women experience this phase varies considerably. Some have barely any symptoms, while others feel significantly affected for years. The duration and combination of symptoms are just as individual.
One more important point: an increasingly irregular or temporarily absent period does not mean the fertile phase is already over. As long as ovulation still occurs, pregnancy remains possible in principle.
Menopause refers specifically to the last spontaneous menstrual period. What makes it unique is that, at the time it happens, a woman doesn't yet know it was her last. Only once twelve months have passed without another period — and no other cause can explain the absence — can that moment be identified retrospectively.
On average, natural menopause occurs at around age 51. However, the range is wide. If it occurs before the age of 45, it is referred to as early menopause. Loss of ovarian function before the age of 40 is termed premature ovarian insufficiency (POI) and should be evaluated medically.
When menopause occurs is strongly influenced by genetic factors, though other factors play a role as well. Smoking, for example, is associated with earlier natural menopause. Ovarian surgery and certain medical treatments can also affect the timing or trigger menopause directly.
Twelve months after the last menstrual period, postmenopause begins. It is not a ten- or fifteen-year window, as is sometimes suggested, but refers to the entire remainder of life after menopause.
The intense hormonal fluctuations of perimenopause now subside. The ovaries produce only small amounts of estrogen and progesterone, while levels of the regulatory hormones FSH and LH remain elevated. This does not automatically mean that all symptoms disappear — hot flashes and night sweats can persist for several more years.
Other consequences of estrogen deficiency may also become more prominent over time. The mucous membranes of the genital and urinary tract change, which can contribute to vaginal dryness, burning, pain during sex, a more frequent urge to urinate, or recurring urinary tract complaints. Specialists refer to these changes collectively as the genitourinary syndrome of menopause (GSM).
Long-term health also comes into sharper focus. With the loss of estrogen's protective effect, bone loss accelerates — particularly in the years around menopause — and the long-term risk of osteoporosis and fractures increases. At the same time, muscle mass and body composition change with advancing age.
The cardiovascular risk profile also shifts after menopause. Physical activity — and strength training in particular — along with a balanced diet and regular preventive care therefore become even more important.
For many women, the menopausal transition begins in their 40s; some notice changes earlier, others later. There is no specific age at which a woman is simply "in menopause." For medical classification, changes in the cycle and typical symptoms are the key factors alongside age.
In women aged 45 and older with typical symptoms, perimenopause can often be assessed clinically based on age, cycle patterns, and symptoms alone. A single hormone test, however, does not necessarily provide clarity: FSH and estrogen levels can fluctuate so considerably during perimenopause that a single measurement offers only a snapshot. Routine hormone testing is therefore generally not necessary for otherwise healthy women over 45 with a typical presentation.
If such changes occur clearly before the age of 45, or if menstruation stops before the age of 40, medical evaluation is recommended.
There is no single answer that applies to all women. The menopausal transition typically spans several years. Postmenopause, in turn, is not a time-limited final phase. Individual symptoms can persist for a long time. The question "How long does menopause last?" therefore has no straightforward medical answer — it depends on whether it refers to the hormonal transition itself or to the duration of symptoms.
The four phases of menopause are primarily a point of orientation. Biologically, the transition is far more fluid. Perimenopause in particular is marked by strong hormonal fluctuations, while after menopause other health considerations move more prominently to the fore.
And if hot flashes, sleep problems, or other symptoms are affecting quality of life, women don't simply have to accept them. Which treatment makes sense depends on the symptoms, age, and each woman's individual health situation.
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