Many women notice physical changes around the age of 40: hot flashes, mood swings, or sleep disturbances. And then the question arises: Is this already menopause? And what exactly is the difference between perimenopause and menopause? This article explains in an easy-to-understand way what happens in the body during both phases, which hormones are involved, and how you can reliably distinguish between them.
Menopause
Many women around 40 notice physical changes: hot flashes, mood swings, or sleep disturbances. And then the question arises: Is this already menopause? And what exactly is the difference between perimenopause and menopause?
While the terms are often used interchangeably in everyday language, they refer to different things. This article will explain in an easy-to-understand way what happens in the body during both phases, which hormones are involved, and how to reliably distinguish between them. For a broader overview, please refer to our complete Perimenopause Guide.
Briefly explained
Perimenopause: the transitional phase before the last period, with fluctuating hormones and irregular cycles.
Menopause: the time of the last period, only confirmed retrospectively after 12 months without bleeding.
Postmenopause: the time after menopause, when estrogen levels remain consistently low.
What is perimenopause?
Perimenopause is the phase leading up to actual menopause. For many women, it begins in their late 30s to mid-40s and can last for several years. It is characterized by significant fluctuations in female sex hormones. Initially, the ovaries' estrogen production gradually declines, leading to the most common first sign: irregular cycles. Typical patterns include shorter or longer intervals between periods, as well as heavier or lighter bleeding. Spotting is also not uncommon.
Hormonally, this phase is a roller coaster. The pituitary gland (hypophysis) secretes more FSH because the inhibiting ovarian hormone inhibin B decreases. At the same time, the ovaries become less sensitive to FSH and LH. Temporarily, estrogen levels can even remain high, while progesterone drops earlier due to less frequent ovulation. This relative excess of estrogen compared to progesterone explains symptoms resembling severe PMS, as well as temporarily heavier bleeding.
What is menopause?
Menopause is the time of the last natural menstrual period. Medically, it is considered to have occurred when there has been no bleeding for 12 consecutive months. It is therefore a single point in time that can only be determined retrospectively. After this, postmenopause begins. On average, menopause occurs around age 51, with significant individual variation. If it occurs before the age of 40, it is called premature menopause (primary ovarian insufficiency) and should be medically investigated.
During menopause, the ovaries have largely ceased hormone production. Ovulation no longer occurs, which means natural pregnancy is no longer possible. Estrogen and progesterone permanently drop to low levels, while FSH and LH remain consistently high due to lack of feedback. The hormonal roller coaster of perimenopause ends, but low estrogen levels persist.
Perimenopause vs. Menopause: a direct comparison
The most important differences at a glance:
| Feature | Perimenopause | Menopause and Postmenopause |
|---|---|---|
| Definition | Transitional phase with fluctuating hormones | Time of the last period, confirmed after 12 months without bleeding |
| Typical age | Often begins late 30s to mid-40s | On average around age 51 |
| Menstruation | Irregular: sometimes shorter, sometimes longer, sometimes heavier, sometimes lighter | Permanently ceases |
| Hormone levels | Highly fluctuating: FSH tends to rise, estrogen sometimes high, sometimes low, progesterone often low | Estrogen permanently low, FSH and LH permanently high |
| Ovulation | Still possible, many cycles occur with ovulation |