When fibroids grow in or near blood vessels, they can cause blockages. These blockages prevent oxygen-rich blood from reaching the tissues and organs of the body. Fibroids that form within arteries are known as "intramural" fibroids, while those that form outside of arteries are called "subserosal." Fibroids that are located at the opening of an artery can also restrict blood flow. If fibroids block the cervix, they may make it difficult for a woman to conceive. Persons having an obstructed blood flow should consult a doctor immediately for treatment. One should also avoid using birth control pills since these may increase the risk of fibroid growth. Taking care of one's health and following a healthy diet can also prevent fibroids from forming.