Fibroid growth, both in the intra- and inter-gravid states, is variable and can range from 18 to 120% per year. In the inter-gravid state, fibroids can grow or undergo spontaneous regression. Factors that can predict fibroid growth include the starting volume of fibroid, type of fibroid and age of patient. In the gravid state, fibroids appears to grow in a non-linear pattern, with the most rapid growth occurring in the first trimester. Factors affecting fibroid growth in pregnancy include the size of fibroids and number of fibroids.