Nobody really knows what causes fibroids. Several factors are implicated, however, and these include hormones, environmental factors and genetic factors.

Increased oestrogen production correlates with fibroids, and it is sometimes observed that fibroids grow during pregnancy, when oestrogen levels are high. Correspondingly, fibroid symptoms tend to improve during the menopause, when oestrogen levels are low. For that reason, some medication can also help with symptoms. Fibroids tend to be rare in women younger than 20, and in postmenopausal women.

However, there is a high rate of incidence of fibroids amongst women of African or Afro-Caribbean origin, while they tend to be rarer in women of East Asian origin. Women with African origin also tend to develop fibroids at a younger age, and tend to have more or larger fibroids than other ethnic groups.

It has also been observed that women who are overweight or obese based on their BMI (body-mass index), and this too may be hormone-linked. Additionally, a sedentary lifestyle and high alcohol consumption have also been associated with fibroids, and some practitioners and sufferers recommend avoiding caffeine.