Understanding Perimenopause and Menopause: What Every Midlife Woman Should Know

In recent years, perimenopause and menopause have finally started getting the attention they deserve— and rightly so. After all, 100% of women who live long enough will experience menopause, yet for decades it was poorly discussed, misunderstood, and under-treated.

What’s the Difference Between Perimenopause and Menopause?

Perimenopause
Perimenopause refers to the transitional years leading up to menopause, when women begin to experience symptoms related to hormonal changes. This phase can last anywhere from a few years to over a decade.
Menopause
Menopause is technically defined as the single day that marks 12 consecutive months without a menstrual period. After that point, a woman is considered postmenopausal , though many people continue to use “menopause” as an umbrella term for this entire life stage.
While not all women experience noticeable symptoms, those who move through perimenopause symptom-free are relatively rare. By age 40, approximately 20% of women are already experiencing some degree of perimenopausal symptoms, with prevalence increasing steadily through the 40s and early 50s.
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Why Symptoms Are So Wide-Ranging

Perimenopausal symptoms are highly individual, variable, and often body-wide, reflecting the profound influence hormones have on nearly every system in the body.


In the later years of perimenopause, estrogen levels fluctuate dramatically — some months they’re higher, other months lower — creating what many women describe as a hormonal rollercoaster. As the ovaries run out of viable eggs, the body actually attempts to recruit them more aggressively, contributing to these swings.


At the same time:

Progesterone steadily declines over the final decade of reproductive life, widening the imbalance between estrogen and progesterone.
Testosterone also gradually decreases , contributing to changes in libido, body composition, energy, and vitality.
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Changes in the Menstrual Cycle

Menstrual changes are often one of the earliest signs of perimenopause.

In the early to mid-40s, cycles commonly shorten
As menopause approaches, periods may space out, be skipped, or become irregular
Some women experience luteal out-of-phase (LOOP) cycles , where periods occur unusually close together—sometimes only weeks apart
Bleeding may become heavier, more frequent, or more painful

Women with heavy or prolonged periods should always be thoroughly assessed for iron deficiency, as low iron can significantly worsen fatigue, brain fog, mood changes, and exercise tolerance. Updated iron-deficiency guidelines now reflect how common and impactful this issue is during perimenopause.