The IUDs can be non-medicated such as Lippes loop, copper-releasing such as CuT, Cu7, Multiload 375 and hormone releasing such as Progestasert, LNG-20, etc. IUDs prevent fertilization from taking place by blocking sperm from entering the fallopian tubes. They also enhance phagocytosis of the sperms. The copper ions reduce sperm motility and fertilizing capacity