Hormones

The hormone-releasing intrauterine device (IUD) functions by releasing hormones to prevent pregnancy, differentiating it from other types of IUDs that may operate using copper. Out of the given options:

• Lippes loop: This is an older form of IUD made of plastic, which does not release hormones. Hence, it is not a hormone-releasing IUD.
• Multiload 375: This is a copper-based IUD that prevents pregnancy by using copper's spermicidal effect, not hormone release.
• Cu 7: This is another copper-bearing IUD characterized by its T-shape and copper components, also not involving hormone release.
• LNG-20: This is the correct option. LNG-20 is a hormone-releasing IUD that releases levonorgestrel, a type of progestin, which contributes to preventing pregnancy through mechanisms such as thickening cervical mucus and inhibiting sperm mobility.

Therefore, the correct answer among the options provided is LNG-20.