Perimenopause: the transition explained

Perimenopause begins years before menopause, often without being recognized: cycles that change, sleep that fragments, roller-coaster moods. Understanding this transition means no longer enduring symptoms you believed were unexplained.

Understanding perimenopause

Perimenopause is the period when the ovaries begin to work irregularly, before periods stop for good. It can start as early as the late thirties and last several years. What makes it distinctive: estrogen levels do not decline gently, they fluctuate, sometimes abruptly. It is this instability, more than the shortage, that explains the feeling of no longer recognizing your own body.

Why it is so hard to identify

Because periods are still there, often until the very end, and because the symptoms resemble those of fatigue, of stress or of a thyroid working poorly. A single blood test generally settles nothing: levels vary from one day to the next. The diagnosis remains above all clinical: age, how the cycle is evolving and the overall pattern of symptoms.

The symptoms that are actually documented

Changes in the cycle, hot flashes, night sweats, night-time awakenings, new anxiety or irritability, brain fog, vaginal dryness, joint pain. On this last point, a longitudinal cohort published in the journal Pain in 2024, which followed 609 women across the stages of menopause, shows that the frequency and intensity of musculoskeletal pain increase as the transition advances, with late perimenopause standing out as a turning point (PMID 38787639). It is an observational study: it establishes a co-occurrence, not causation.

The trap to avoid: blaming everything on hormones

This is the most important point on this page. Perimenopause arrives at an age when other things happen too: thyroid disorders, anemia from heavy periods, sleep apnea, depression, inflammatory diseases in their early stages. The SWAN cohort showed that the symptom profiles of women in this age group were already present before the transition and remained fairly stable (PMID 29326841). In other words, menopause explains part of the picture, rarely all of it.

Signals that deserve medical advice

Very heavy or prolonged bleeding, bleeding between periods or after intercourse, fatigue that worsens despite sleep, a joint that swells or becomes warm, morning stiffness that lasts well beyond a few minutes, unusual shortness of breath. None of these signs means something serious is going on, but each deserves to be looked at rather than automatically put down to "age".

This page is educational. It makes no diagnosis and does not replace a medical consultation.

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