Fibroids in perimenopause: why they flare then shrink

Why perimenopause is the worst phase

Fibroids grow in response to estrogen and progesterone, and they carry a higher density of receptors for both than normal uterine muscle does.

The intuitive expectation is that declining hormones shrink them. What actually happens first is the opposite: perimenopausal estrogen fluctuates and its peaks can exceed premenopausal levels, so fibroids can grow and symptoms intensify in the years before periods stop.

Add the heavy, disorganised bleeding of cycles without ovulation, and the two effects compound. This is why the forties are so often when fibroids finally become unmanageable after years of being tolerated.

What they cause

Many fibroids cause nothing at all. When they do, it depends on size and position:

• Heavy, prolonged bleeding, with clots — the most common symptom
• Pelvic pressure, fullness or a visibly enlarged abdomen
• Pain during periods or during sex
• Needing to pass urine often, from pressure on the bladder
• Constipation, from pressure on the bowel
• Iron deficiency and its fatigue, from the bleeding
• Lower back or leg discomfort with larger fibroids

What happens after menopause

Without ovarian estrogen, fibroids typically shrink and symptoms improve, often substantially. This is why waiting it out is a legitimate option for some women close to the end of the transition, and why the decision often turns on how many years are likely left rather than on the fibroid itself.

Hormone therapy does not usually cause significant fibroid growth, but it can slow that natural shrinkage and occasionally causes bleeding problems in women with fibroids. It is a reason to mention them when discussing treatment, not a reason to rule it out.

The exception that matters

A fibroid that grows after menopause is not behaving as fibroids behave, and it should be assessed rather than monitored casually. The same applies to new pelvic pain or new bleeding after menopause in someone with known fibroids.

Uterine sarcoma, a rare cancer that can resemble a fibroid on imaging, is the reason for the rule. It is uncommon, and that is precisely why the unusual pattern is the one that gets looked at.

When to see someone

Heavy bleeding, pelvic pressure or urinary frequency in your forties deserves an ultrasound rather than being folded into a general perimenopause discussion. Fibroids are readily visible and their size and position change which options apply.

Ask for ferritin as well. Iron deficiency from fibroid bleeding is extremely common and frequently untreated.