Epidemiologic characteristics of women with uterine fibroids: a case-control study.

Risk factors for uterine fibroids were analyzed in a hospital-based case-control study conducted in the greater Milan area, based on 275 women with histologically confirmed fibroids and 722 controls with acute nongynecologic or hormone-related conditions. Questions were asked about menstrual and reproductive characteristics, education, history of various diseases, and lifetime use of oral contraceptives and other hormonal treatments. The risk of uterine fibroids was reduced in parous women relative to nulliparous ones (relative risk 0.6) and in those who were postmenopausal (relative risk 0.1 compared with premenopausal women of the same age). Women with fibroids tended to have an earlier age at menarche and at the last birth, to be more educated, and to use intrauterine devices and oral contraceptives more frequently, although these findings were not statistically significant. Current smoking (but not past smoking) lowered the fibroid risk by about 40%. No associations were found with body mass index, history of spontaneous or induced abortions, and age at first birth.