Copper releasing $IUDs (CuT$, multiload) increase phagocytosis of sperms within the uterus and the $Cu$ ions released suppress sperm motility and the fertilising capacity of sperms. $IUDs$ are inserted and removed by trained doctors. $ IUDs$, once inserted can be there for a long period of time (even years). But eventually they need to be removed and replaced, as they are foreign to the body. Fertility returns, once $IUDs$ are removed.