What are uterine fibroids?

Uterine fibroids are the most common form of non-cancerous (benign) tumours in women of reproductive age. They are also known as leiomyoma, leiomyomata, or myoma. They can grow anywhere in the womb and may cause different symptoms depending on their location. Fibroids are usually round or semi-round in shape and can range in size from a pea to a melon.


Around one in every three women with fibroids may experience symptoms which could interfere with daily life. Talk to your doctor if you experience these symptoms.

During your period, the body releases chemicals that cause the muscles in the womb to contract. When these muscles contract it can cause pain.

You should be able to tell if your periods become very heavy if you need to change your sanitary products every hour or two. Additionally, if you are passing blood clots larger than 2.5cm (about the size of a 10p coin), need to use two types of sanitary product together – for example, tampons and pads, or are bleeding through to your clothes or bedding, your periods may be classed as heavy. Heavy periods can have an emotional and social impact and lead to iron-deficiency anaemia, and tiredness.

If a period lasts longer than seven days, it may be deemed irregular. Additionally, if there are less than three weeks between the start of one period and your next, if you have bleeding between cycles or bleeding after sex this may also indicate fibroids.

Fibroids can cause pain or swelling in the pelvis. When a uterine fibroid is present in a particular area of the womb, vaginal penetration may cause a direct, sharp pain, making sex nearly impossible to enjoy.

You may have to go to the toilet more frequently if fibroids press on the bladder. Fibroids may press on the large intestine, causing constipation and pain during bowel movements.

Some women can experience pain during sex because the fibroids press on the cervix, which can have an impact on relationships.

Occasionally, fibroids can lead to problems with becoming pregnant or infertility (the inability to become pregnant).
Infertility can happen if fibroids are very large or submucosal, where they grow into the cavity of the womb. Depending on their type and size, fibroids can sometimes prevent a fertilised egg from attaching itself to the lining of the womb, or they may block the fallopian tube, making pregnancy difficult.
In some cases, fibroids may also lead to complications during pregnancy for both the mother and child, increasing the risk of miscarriage and can cause problems during labour.

If you think you may have some symptoms of uterine fibroids, download our symptom checklist form. Tick the boxes of the symptoms you are experiencing and take this to your doctor to discuss during your appointment:

Download Symptom Checker PDF Here


Fibroids have different names and descriptions based on their location within the womb (uterus).

  • Intramural fibroids: within the muscle wall of the womb
  • Pedunculated fibroids: attached by a stalk to the outside or inner wall of the womb
  • Submucosal fibroids: inner wall into the womb
  • Subserosal fibroids: outside wall of the womb into the pelvis

Impact on daily life

Fibroids can cause health problems, which can make daily life more difficult compared with women without fibroids. Talk to your doctor if you feel you need help in dealing with these daily problems.

  • Abnormal menstrual bleeding, which can be irregular and/or heavy periods
  • Pregnancy complications because fibroids disturb the reproductive cycle, difficulty in becoming pregnant, increased risk of miscarriage and pre-term birth
  • Problems related to fibroid mass or bulk in the womb, such as:
    • Pressure or pain in the pelvis
    • Frequent urination and constipation or painful bowel movements
    • Pain or discomfort during sex


There are many risk factors associated with fibroids and hormonal changes can promote their occurrence:

Fibroids are more prevalent in peri-menopausal women (approaching menopause). However, they can occur in women of reproductive age.

If members of your family have had fibroids, you may be at higher risk of developing the same condition.

Fibroids are thought to occur more often in women of African-Caribbean origin.

Women who started their period when 10 years old or younger have a higher risk of fibroids when compared with women who were 12 years or older at the time of their first period.


Women who have given birth have a lower risk of developing fibroids. This may be because pregnancy limits exposure to high levels of oestrogen.

Menopause limits oestrogen and progesterone levels and therefore women who have gone through the menopause have a lower risk of developing fibroids, as fibroids tend to shrink when deprived of oestrogen.

There is a higher risk of fibroids in overweight women. This is likely due to hormone interactions associated with obesity.

Women who exercise regularly may have a reduced risk of developing fibroids.

Women with high blood pressure have a higher likelihood of developing fibroids due to additional pressure on the cardiovascular system.