Figure 3: Types of IUD. (a) Lippes loop (patent number US3802425 A). Many investigators support the use of a Lippes loop of IUD. (b) T-shaped (patent number US4026281 A). IUDs are thought to have too small surface area to be truly effective in providing a physical barrier. (c) Uterine-shaped (patent number CN201220343083) IUD. The uterine-shaped IUD was originally manufactured in Chongqing, Sichuan. It is designed in the shape of the uterine cavity, consisting of a stainless steel coiled wire framework with copper added inside the coil wire, and releases anti-inflammatory agent. The uterine-shaped IUD is the most commonly used IUD in China. (d) Multiload Cu 375 (patent number EP2198815 A1). This IUD consists of a copper-bearing plastic shaft and two small flexible curved side arms. Some authors suggested that the copper-containing IUDs provoke an inflammatory reaction. (e) Recently, a new type of uterine-shaped IUDs was researched and manufactured in China with China patent number Zl 2008 2 0052366.3 and (f) another new product with a China patent number Zl 2012 20070407.8; this type of devices is only used for IUA.