Fibroids are benign growths or tumours on the muscular part of the uterus (the womb). They are not cancer.
Fibroids can be very small or bigger than the size of a grapefruit. They can grow in various positions on the uterus. The symptoms a woman has will depend on the number, size and position of the fibroids.
Twenty-five to 40 per cent of women of child-bearing age have fibroids. They are more common in women who are overweight or in women who are having trouble becoming pregnant. Most fibroids are diagnosed when women are between 30 and 40 years of age. They are often found when a woman is being examined during pregnancy or when having a cervical smear.

What causes fibroids?

It is not known what causes fibroids. Fibroids are more likely to grow when there are high levels of oestrogen in the body. This explains why fibroids tend to grow during pregnancy when oestrogen levels increase and why they reduce in size at menopause when oestrogen levels fall.
There is some evidence that women are more likely to have fibroids if other women in the family have had them.

Many women do not know they have fibroids as they have no symptoms. Others can have symptoms which include:

• Heavy or irregular bleeding Fibroids are often the cause of heavy periods for women in their thirties and forties. The heavy loss of blood can lead to tiredness and anaemia (low iron levels).
• Painfulperiods Sometimes, when a woman has her period, there are strong contractions as the uterus tries to push out fibroids growing inside it.
• Pain in the lower abdomen, pelvis or back. Fibroids can cause pain by pressing on internal organs or by being connected to other organs by scar tissue.
• Passing urine more frequently or having difficulty having a bowel motion. Fibroids can press on the bladder or bowel causing women to pass urine more frequently or to have difficulty in passing a bowel motion. Sometimes the pressure can be uncomfortable or painful.
• Swelling of the lower abdomen. This can happen when fibroids are large.

A woman who has any of these symptoms regularly should check with her doctor to find out the cause and to look at possible treatments.