There is no underlying cause in 40-60% of cases of heavy periods (menorrhagia).
Otherwise, possible causes of heavy periods include the following:
- cervical or endometrial polyps: these are non-cancerous growths in the womb or the lining of the cervix (neck of the womb)
- endometriosis: this is when small pieces of the womb lining are found outside the womb; for example, in the fallopian tubes, ovaries, bladder or vagina
- uterine fibroids: these are non-cancerous growths in the womb that can cause pelvic pain
- intrauterine contraceptive devices (IUD), also known as 'the coil': blood loss may increase by 40-50% after an IUD is inserted
- pelvic inflammatory disease (PID): this is an ongoing infection in the pelvis that can cause pelvic pain, fever and bleeding after sexual intercourse or between periods
- polycystic ovary syndrome (PCOS): women with PCOS typically have a number of cysts in their ovaries
- blood clotting disorders such as von Willebrand disease
- an underactive thyroid gland (hypothyroidism): this may cause fatigue, constipation, intolerance to cold and hair and skin changes
- liver or kidney disease
- cancer of the womb (although this is very rare)
Treatments that can cause heavy periods
Heavy periods may sometimes be caused by medical treatments. These can include:
