Copper-based intrauterine contraceptive mechanism (None established (often referred to generically as "Cu-IUD" in literature))

Copper IUDs are contraceptive devices made from plastic and wrapped in copper wire, which are inserted into the uterus for long-acting, reversible birth control. The presence of copper triggers a local, cytotoxic inflammatory reaction in the endometrial lining and uterine cavity, which is hostile to sperm and prevents fertilization. Copper ions directly impair sperm motility and viability, and alter mucus at the cervix, hindering sperm passage. Clinical evidence supports that copper IUDs work predominantly by preventing fertilization, not by averting implantation or causing abortion. Copper IUDs are hormone-free, effective for up to 10-12 years, and commonly used worldwide.

Other names

Copper intrauterine device mechanismCu-IUD mechanismCopper coil actionParagard mechanismnon-hormonal IUD mechanism

Release of copper ions from the IUD device into the uterine cavity. Copper ions are toxic to sperm, inhibit their motility, and viability. Copper enhances local inflammatory response, with leukocyte infiltration that also destroys sperm. May alter cervical mucus, making it hostile to sperm. May also prevent implantation (secondary, not primary mechanism).