IUDs which are used by females
release copper ions in the uterus that increase phagocytosis of sperms
IUDs are T-shaped intrauterine devices containing either copper or progesterone which are inserted by doctors into the uterus through vagina. They are a form of long reversible contraceptive methods.
They prevent contraception by increasing the phagocytosis of sperms within the uterus thus, making it unsuitable for implantation. They also suppress sperm motility and fertilising ability of sperms, e.g. Cu-T, Cu-7, LNG-20, Mirena, etc.