PIP: Estrogen stimulation of myometrial cells may contribute to the development of uterine fibroids. Fibroids have more estrogen receptors than has the nearby normal myometrium. Fibroids are rare before menarche and usually regress after menopause, suggesting that growth factors affecting the growth of uterine smooth muscle cells and fibroblasts may mediate the estrogen effect. Prospective studies do not support the clinical notion that fibroids increase during pregnancy. In fact, as parity increases the risk of fibroids decreases. Early high-estrogen-dose oral contraceptives (OCs) may have contributed to the development of uterine fibroids, but as the progestogen dose increased, these OCs have been associated with a decrease in uterine fibroids (e.g., 17% reduction for every 5 years of OC use). Thus, unopposed estrogen stimulation appears to increase the risk of uterine fibroids. The presence of uterine fibroids should not be a contraindication for OC use. OCs with an adequate dose of progestogen may have a protective effect. Since Norplant implants and the injectable Depo-Provera have only a progestogen, they are not likely to increase the risk of uterine fibroid development or growth. In fact, Depo-Provera has been successfully used to treat women with fibroids suffering from menorrhagia and dysmenorrhea. IUDs can exacerbate menorrhagia, dysmenorrhea, and anemia in women with fibroids. Women with fibroids often have unusually large and distorted endometrial cavities, so an IUD may not fit the shape of the patient's uterus. No published data on pregnancy and expulsion rates in IUD users with uterine fibroids exist.