What perimenopause actually is
Perimenopause is the transition period leading up to menopause — the point when you've gone 12 consecutive months without a period. It typically begins in the mid-to-late 40s, but can start as early as the late 30s. During this phase, oestrogen and progesterone levels fluctuate erratically rather than following the predictable monthly pattern of earlier reproductive years. It's these fluctuations, not just declining levels, that cause most symptoms.
Symptoms that go unrecognised
Hot flushes and night sweats are well known, but perimenopausal women frequently experience symptoms that are rarely attributed to hormones: sudden anxiety or a low mood that comes out of nowhere, significant sleep disruption, heart palpitations, joint aches, brain fog and difficulty concentrating, and changes in libido. These are often attributed to stress, depression, or ageing — missing the hormonal cause entirely. If you're in your 40s and have a cluster of these symptoms, ask your gynaecologist about perimenopause.
The cycle changes to watch for
Cycle irregularity is usually the first noticeable sign. Periods may become shorter, longer, lighter, heavier, or simply unpredictable. Some months you may skip entirely; others you may have two. Flooding — very heavy bleeding that soaks through protection quickly — is also common in perimenopause and, while usually benign, should always be evaluated to rule out fibroids or other causes. Tracking your cycle during this period is genuinely useful data for your doctor.
When diagnosis is tricky
There is no definitive blood test for perimenopause. FSH rises as ovarian reserve declines, but levels fluctuate so much during the transition that a single result is not diagnostic. Your gynaecologist will typically make the diagnosis based on your symptoms, age, and menstrual pattern rather than lab values alone. This is why it's important to describe all your symptoms — not just the gynaecological ones — at your appointment.