Some women lose an excessive amount of blood during their period. The medical term for heavy periods is ‘menorrhagia’. It can sometimes happen along with other symptoms too, such as period pain.
Heavy bleeding doesn’t necessarily mean there’s anything seriously wrong, but it can affect a woman physically and emotionally, and disrupt everyday life.
See your doctor if you’re worried about heavy bleeding during or between your periods.
How much is heavy bleeding?
It’s difficult to define exactly what a heavy period is because this varies from woman to woman. What’s heavy for one woman may be normal for another.
The average amount of blood lost during a period is 30-40 milliliters (ml), with 9 out of 10 women losing less than 80ml. Heavy menstrual bleeding is considered to be 60ml or more in each cycle.
However, it’s not usually necessary to measure blood loss. Most women have a good idea about how much bleeding is normal for them during their period and can tell when this amount increases or decreases.
A good indication that your blood loss is excessive is if:
- You feel you’re using an unusually high number of tampons or pads
- You experience flooding (heavy bleeding) through to your clothes or bedding
- You need to use tampons and towels together
What causes heavy periods?
In some cases, the cause of heavy periods can’t be identified. However, there are a number of conditions and some treatments that can cause heavy menstrual bleeding.
Conditions that can cause heavy bleeding include:
- Polycystic ovary syndrome (PCOS) – a common condition that affects how the ovaries work; it causes irregular periods and when periods return they can be heavy
- Pelvic inflammatory disease (PID) – an infection in the upper genital tract (the womb, fallopian tubes or ovaries) that can cause pelvic or abdominal pain and bleeding after sex or between periods
- Fibroids – non-cancerous growths that develop in or around the womb and can cause heavy or painful periods
- Adenomyosis – when tissue from the womb lining becomes embedded in the wall of the womb
- Endometriosis – when small pieces of the womb lining are found outside the womb, such as in the fallopian tubes, ovaries, bladder or vagina (although this is more likely to cause painful periods)
- An underactive thyroid gland (hypothyroidism) – where the thyroid gland doesn’t produce enough hormones, causing tiredness, weight gain and feelings of depression
- Cervical or endometrial polyps – non-cancerous growths in the lining of the womb or cervix (neck of the womb)
- Blood clotting disorders, such as Von Willebrand disease
- Cancer of the womb (although this is relatively rare)
Medical treatments that can sometimes cause heavy periods include:
- An IUD (intrauterine contraceptive device, or ‘the coil’) – this can make your periods heavier for the first three to six months after insertion
- Anticoagulant medication (taken to prevent blood clots)
- Some medicines used for chemotherapy