Fibroids are found to be more prevalent, occur at a younger age, and grow faster among African-American women than any other race. Vitamin D is essential in the synthesis of steroid hormones. Lack of vitamin D leads to sub-optimal levels of critical hormones in the body, which is a contributing factor to the incidence of fibroids.

Drugs such as Clomid, which are used to treat infertility in women, have been implicated in causing fibroids or increase their growth.

Emotional stress is not taken seriously since the effect of emotions on the general functioning of the body is neglected. Emotional breakdown, stress, and depression are related to hormone levels. When under emotional stress, a lot of progesterone is converted to stress hormone cortisol, which eventually depletes progesterone and increases the levels of estrogen. High levels of estrogen is one of the major contributing factors to fibroids. Emotional stress is probably one other reason why fibroids are common between the ages 40 and 50 years.

Growth factors play an important role in cell proliferation. Abnormalities in these proteins may lead to fibroids. Studies show that Transforming Growth Factor Beta (TGF beta) and Epidermal Growth Factors (EGF) are present in the cells of fibroid tissue, suggesting that they play a role in these abnormal growths.

It is not known if obesity has a direct impact on causing fibroids, but obesity has been found to increase the possibility of fibroids by 2 to 3 times, as compared to a woman of average weight. The possible relation could be that obesity causes several complications, such as high fat accumulation and hormonal imbalance, which in turn cause fibroids.

In our day to day life, we get exposed to various toxins from the environment through breathing polluted air, drinking unsterilized water, exposure to chemicals and heavy metals, etc. All of these have an effect on the internal system, which might reflect on the disruptive functioning of organs, variation in hormone levels, gene mutation, etc. Consequently, such dysfunctions can lead to various complications, fibroids being one of them. In this regard, excessive consumption of fat can also be a contributing factor for causing fibroids since cholesterol is the precursor of estrogen.

It is important that estrogen and progesterone are maintained at optimal levels in the body. Xenoestrogen and progesterone produced in excess can cause uterine fibroids. Estrogen administered externally is called xenoestrogen and is usually supplemented post menopause when the estrogen level falls. This is one important reason why fibroids are common in women between 40 and 50 years of age. On the other hand, in younger women fibroids are found to grow during the luteal phase when progesterone levels are high. Also, women on contraceptive pills are more prone to fibroids since the pills are progesterone pills.

Many cases of fibroids, on medical investigation, are found to recur in the same family. Women whose mother, grandmother, or sister have been affected by fibroids are more predisposed to this disease. This is because the mutated gene is transmitted to the future generations. Sporadic mutations may also occur causing the disease, but it is less common.

Mutation in specific genes has been found to cause fibroids. One such gene is fumarate hydratase (FH), a house keeping gene, which is important for energy production inside the cell. When this gene gets mutated, and fails to produce a functional protein, or produces the protein in low quantities, or does not produce the protein at all, it can result in fibroids.

A group of scientists from University of Helsinki, Finland have identified another gene MED 12 to cause 70% of the 225 different types of fibroids. This gene is said to be involved in transcriptional regulation of genes.