Can uterine fibroids cause bleeding between periods?

Yes, uterine fibroids can cause bleeding between periods. Heavy menstrual bleeding is the most commonly experienced symptom in women who have uterine fibroids, but the tumors can also cause breakthrough bleeding, or bleeding between periods. The larger fibroids become, the more likely they are to cause abnormal bleeding.

Uterine fibroids are also known to cause longer and more painful periods. All of these menstrual issues are related to the size and location of the fibroids, as bleeding symptoms are more likely to occur when fibroids are compressing the uterus or enlarging the interior lining of the uterus, called the endometrium.

Hormones play a role in the growth of fibroids and their symptoms. The naturally occurring female steroid hormones estrogen and progesterone are known to stimulate fibroid growth, and researchers believe that these hormones are the main mechanism by which fibroids grow and multiply.

There are times during a woman's reproductive life cycle that fibroids are more likely to occur. During pregnancy, fibroids grow very quickly because the levels of these hormones are so high. Uterine fibroids are most common in women between the ages of 30 and 40, but abnormal bleeding symptoms usually decline after menopause when less hormones are produced.

Additionally, fibroids can cause higher levels of prostaglandins. These hormones, responsible for igniting the body’s healing response, control blood flow by stimulating blood clots to form and/or promoting blood vessel contraction. While prostaglandins normally regulate the reproductive system, elevated prostaglandin from fibroids causes abnormal or excessive bleeding.

Therapies to manage abnormal bleeding involve the regulation of estrogen, progesterone and prostaglandin.