Uterine fibroids are very common. 1 in 3 women at the age of 40 will have a fibroid.
The uterus is a muscle. If a muscle cell of the uterus decides to start dividing it forms a small ball of muscle. This is a fibroid. It grows very slowly over time, of the order of 1cm per year.
It is possible for fibroids to cause heavy bleeding, pain, difficulty falling pregnant or miscarriages. If they are large they can cause bladder or bowel symptoms. However most of the time they are small and do not cause any problems at all.