Perimenopause and Menopause

Perimenopause is the endocrine transition most often identified from a calendar rather than from a laboratory report. A lasting change in cycle length comes first, then skipped cycles, then twelve months with no period at all. Hormone output swings so widely across this stretch that a single blood draw describes a week rather than a stage. The fourteen answers in this topic share one organising idea, and this page sets out what that idea is and what order to think in.

The pattern carries the diagnosis, not the blood test

The cost of testing first is not the price of the test. A normal FSH result gets used to close a conversation that should have stayed open, and a raised one gets used to explain symptoms that had a separate cause sitting behind them. Blood work belongs in this assessment. It earns its place by excluding the conditions that imitate the transition, not by confirming the transition itself. Two consequences of staging get missed in ordinary consultations. Pregnancy remains possible until twelve months have passed without a period, so contraception stays a live question through the forties. The clock on bone loss and on cardiovascular risk is set by the date of the final period rather than by a birthday, which is why that date is worth writing down.

The metabolic shift starts before the last period

The Study of Women's Health Across the Nation measured body composition across the transition and published the result in JCI Insight in 2019. The rate of fat gain doubled, from about 1.0 percent a year before the transition to about 1.7 percent a year during it. Lean mass turned the other way, from a small annual gain to a loss of about 0.2 percent a year. The acceleration began roughly two years before the final menstrual period and flattened about a year and a half afterwards. Across that window of some three and a half years the average woman gained around 1.6 kg of fat while losing lean tissue.

The part that should change what you measure is this. Body weight in the same cohort rose in a straight line through the whole period, with no step upward when the transition began, because fat gained and lean lost offset each other on the scale. A woman weighing herself every week through her late forties can see almost nothing while her composition changes underneath. Waist circumference, a strength measure you repeat, blood pressure, HbA1c and a lipid panel that includes ApoB describe this shift better than weight does. The timing argues for acting early, since the final period can only be identified twelve months after it has already happened.

How to read any hormone therapy risk number

Four questions make almost every hormone therapy statistic readable. Which arm produced it, estrogen alone or estrogen combined with a progestogen. What age the women were when they started. Whether the number is absolute or relative. And which outcome it describes, over what length of follow up. The Women's Health Initiative enrolled women at an average age of 63 and its two arms returned different answers, so a figure quoted without its arm and its starting age is close to unreadable.

The Menopause Society set out the timing position in its 2022 hormone therapy statement: "For women aged younger than 60 years or within 10 years of menopause onset and without contraindications, the benefit-risk ratio appears favorable for treatment of bothersome vasomotor symptoms and for the prevention of bone loss and reduction of fracture." One element here is genuinely contested. The randomised estrogen alone arm of the Women's Health Initiative found no increase in invasive breast cancer. The 2019 individual participant meta-analysis by the Collaborative Group on Hormonal Factors in Breast Cancer, published in The Lancet and built on observational data, reported a relative risk of 1.33 for estrogen only preparations used five to fourteen years, roughly one extra case per 200 women starting at age 50. Randomised and observational evidence disagree, and that disagreement is unresolved.

What to exclude before blaming the transition

Fatigue, weight change, low mood, thinning hair and broken sleep are the symptoms perimenopause shares with hypothyroidism, iron deficiency, sleep disordered breathing and depression. Each one is common in women in their forties, each is treatable, and each disappears easily into a perimenopause label. Mood deserves a specific note. SWAN found raised odds of major depression during the transition compared with premenopause, yet among women who had never had a major depressive episode, menopausal status did not predict a first one. Previous anxiety and stressful life events did. Treat a mood problem as a mood problem rather than waiting for hormone therapy to resolve it.