What mechanism of action does the copper IUD employ to prevent pregnancy?

The copper IUD primarily prevents pregnancy by creating a toxic environment for sperm. The copper ions released from the device have a detrimental effect on sperm motility and viability, which significantly reduces the chances of fertilization. Additionally, the presence of the IUD in the uterus triggers a local inflammatory response that is hostile to both sperm and ova, further contributing to its effectiveness as a contraceptive method.

While altering the uterine lining, releasing hormones, and preventing ovulation are mechanisms used by other forms of contraception, such as hormonal IUDs or systemic hormonal contraceptives, the copper IUD does not function through these pathways. Its efficacy relies primarily on the spermicidal properties of the copper material itself and the resulting local inflammatory environment.