Detailed definition
Perimenopause, also called the menopausal transition, is the period of menstrual cycle and endocrine changes that precedes menopause. It usually begins in the mid-to-late 40s but can start in the late 30s. Hallmarks include: variable cycle length (a difference of 7+ days between consecutive cycles is the early-perimenopause marker in STRAW+10); skipped cycles; rising and erratic FSH; declining inhibin B and AMH; estradiol fluctuations that are often higher than premenopausal levels in the early transition before falling; and the onset of vasomotor symptoms, sleep disruption, mood changes, and cognitive symptoms. By definition perimenopause ends 12 months after the final menstrual period, at which point a woman is considered postmenopausal. The full transition typically lasts 4 years on average but can extend 7–10 years.
Why it matters in menopause
The biggest gap in women's healthcare is undertreated perimenopause. Many women in their 40s present with sleep disruption, brain fog, mood changes, and irregular cycles, are told their FSH "looks fine," and are sent home. By NAMS guidance, perimenopause is a clinical diagnosis based on symptoms and cycle change in a woman of typical age — labs are not required. ClearedRx and modern menopause practices treat perimenopause with the same HRT options used in postmenopause, often with a low-dose oral contraceptive option for women still cycling.
Related terms
Sources
External references: Wikipedia.