AbstractThe use of copper-containing intrauterine devices (Cu-IUDs) is a safe, effective, and long-term contraceptive method. Here, we review the effects of Cu-IUDs on subsequent pregnancy and the morphology, local coagulation function, sensitivity to estrogen and progesterone, cell proliferation, and immune response of the endometrium. Studies on the morphology of endometrium indicate that the use of Cu-IUDs can affect the number and binding capacity of estrogen and progesterone receptors in the endometrium and reduce the response of the endometrium to estrogen and progesterone. The use of Cu-IUDs can also affect the proliferation of endometrial cells, suggesting that the aseptic inflammation caused by Cu-IUDs may differ from chronic infectious or noninfectious inflammation; this highlights that the use of Cu-IUDs provides protection against endometrial proliferative diseases. The use of Cu-IUDs increases local endometrial angiogenesis, bleeding tendency, and fibrinolytic activity, which can result in prolonged menstruation or abnormal uterine bleeding. Additionally, the use of Cu-IUDs can cause the infiltration of numerous lymphocytes, monocytes, macrophages, and other inflammatory cells around the endometrial gland and changes in endometrial immune function, immune cell function, and the number and type of immune molecules. Cu-IUD-induced decidual injury significantly increases the invasiveness of trophoblasts, further affecting the aberrant expression of their growth-, angiogenesis-, and invasion-related factors and improving the formation of the placenta. Moreover, the endometrial damage caused by Cu-IUD placement before embryo transfer can improve both clinical pregnancy and live birth rates; however, specific changes in the immune system after Cu-IUD use as well as its effects on future pregnancies require further investigation.
