Perimenopause
Mid-40s
Sometimes late 30s
- How long
- Until menopause; often 4 to 10 years
- What’s happening
- Estrogen swings high and low; progesterone falls as ovulation becomes irregular.
- What you might notice
- Cycles shift, sleep breaks, mood changes, first hot flashes.
Perimenopause usually begins in your mid-40s, sometimes in your late 30s. It lasts until you reach menopause, which can be anywhere from 4 to 10 years, depending on when your periods stop. This is the stage most symptoms belong to, and it starts while you’re still having periods.
What’s happening: the ovaries respond less reliably to the brain’s signals. Some months estrogen spikes higher than it ever did; other months it crashes. Ovulation becomes irregular, so progesterone, which is made after ovulation, drops first. Cycles may vary by a week or more and may get shorter. For some women they later lengthen and skip. A gap of 60 days or more can be a sign of middle to late perimenopause.
What it feels like: sleep problems, mood changes, heavier or unpredictable periods, and symptoms like hot flashes may arrive in this stage, while blood tests may still read “normal.” Fertility is low but not gone; see the question on pregnancy.



