Risk factors for copper T IUD expulsion: an epidemiologic analysis.

Little is known of the factors associated with expulsion of intrauterine devices (IUD). We conducted a nested case-control study to examine the risk factors for copper T IUD expulsion using data from a multicenter international clinical trial. We included 70 cases with expulsion and 1,536 controls, and we examined a variety of characteristics of the IUD wearers. The proportional hazards model showed that young maternal age, abnormal amount of menstrual flow and dysmenorrhea before IUD insertion are risk factors for copper T IUD expulsion. The risk of expulsion steadily increased as age decreased, and as the severity of dysmenorrhea increased.