Background: The aim of this study was to determine the effects of a copper-releasing intrauterine device (IUD) on myometrial contractility midway through the menstrual cycle.
Study design: Uterine peristalsis was studied midway through the cycle with transvaginal sonography in two groups of women, a control group and women in whom a copper-releasing IUD had been inserted.
Results: The results showed that 12 months after insertion, no uterine motility could be detected with sonography in any of the women with an IUD, but motility did occur in all the controls.
Conclusions: Subendometrial-myometrial contractility midway through the menstrual cycle had been abolished in patients with a copper-releasing IUD. The loss of motility may inhibit sperm transport from the cervix to the oviduct and account for at least part of the contraceptive effect of these devices.