Where do fibroids come from?
No one knows exactly what causes fibroids (also called leiomyomas and myomas). But their growth — though not necessarily their cause — is related to estrogen and possibly progesterone. Several things suggest their dependence on hormones: Fibroids seldom occur before the first menstrual period; pregnancy can spur their growth; and they often shrink after menopause. Faulty genes may play a role, possibly accelerating the growth of uterine muscle cells. Abnormalities in uterine blood vessels may also be involved.
