How do oral contraceptives affect uterine fibroids?

Researchers think that taking oral contraceptives may reduce the risk for uterine fibroids. This may not be true for women who start taking them between the ages of 13 and 16, but it seems to be the case for all other age groups. Sometimes, certain oral contraceptives - especially those that contain progestin - are actually used as a treatment for uterine fibroids because they may control excessive menstrual bleeding, even though they do not reduce fibroid size. However, this is usually just a temporary treatment because symptoms may return as soon as women stop taking the oral contraceptives.