What causes heavy menstrual bleeding?

Understanding the causes

Heavy menstrual bleeding (HMB) can result from a variety of underlying conditions, changes in the womb, or hormonal factors. Sometimes, no clear cause is identified. Knowing the possible reasons can help guide the right treatment.

Common gynaecological causes

Fibroids: non-cancerous growths in the muscle of the womb that can make periods heavier or longer.
Polyps: small growths in the lining of the womb (endometrium) that may cause heavy or irregular bleeding.
Endometriosis and adenomyosis: conditions where tissue similar to the womb lining grows outside or within the muscle wall, often leading to pain and heavy bleeding.

Hormonal and ovulation-related causes

Hormonal imbalance: if the ovaries do not release an egg (anovulation), hormone levels may fluctuate, causing heavier bleeding.
Perimenopause: changing hormone levels in the years leading up to menopause can lead to heavier or unpredictable periods.

Medical conditions

Thyroid problems: underactive or overactive thyroid can affect menstrual cycles.
Blood clotting disorders: conditions such as von Willebrand disease may make bleeding heavier.
Pelvic infections: long-term infections can sometimes affect menstrual flow.

When no clear cause is found

In some cases, no obvious cause is identified. This is called dysfunctional uterine bleeding and may still be managed with medication or procedures to reduce symptoms.

Why causes matter

Identifying the cause of HMB is key to choosing the most effective treatment — whether that’s medication, hormonal therapy or surgical options.

At Transform Femme, your consultant gynaecologist will carry out a thorough assessment, which may include blood tests, scans or hysteroscopy, to help identify the underlying reason for your symptoms.

Frequently Asked Questions

Can fibroids cause heavy bleeding?

Yes. Fibroids are one of the most common causes of heavy periods.

Is heavy bleeding always caused by a medical condition?

Not always. Sometimes no clear cause is found, but treatment can still help.

Can thyroid problems affect my periods?

Yes. Both underactive and overactive thyroid can lead to heavy or irregular periods.

Does endometriosis always cause heavy bleeding?

Not always. Some women have pain without heavy bleeding, while others experience both.

What if doctors can’t find a cause?

Even if no cause is found, there are treatments available to reduce bleeding and improve quality of life.