The first modern IUDs—the Lippes Loop and the Margulies Spiral—appeared in the early 1960s. They were made of polyethylene, a biologically inert plastic (137, 216). In the late 1960s researchers discovered that adding copper to a plastic IUD frame increased effectiveness, thus allowing sizes smaller than the all-plastic devices. The first copper IUDs—the Cu-7 and TCu-200—proved to cause fewer side effects such as pain and bleeding. They were just as effective in preventing pregnancy, however (370, 454). It was thought that these IUDs would have to be replaced every few years. Therefore a second generation of copper IUDs was developed, including the TCu-380A, the TCu-220C, the Nova T, the Multiload-375 (MLCu-375), and others. These IUDs last longer and are even more effective. IUDs that release a hormone in the uterus also were developed in the 1970s (5, 530).

International donor agencies are now providing second-generation copper IUDs for use in developing-country programs. The United States Agency for International Development (USAID), one of the major international donors of IUDs, began supplying the TCu-380A in 1985, the year after the IUD was approved by the United States Food and Drug Administration (US FDA) (547). Because this IUD is effective and long-lasting, USAID now supplies only the TCu-380A in response to programs that request IUDs (401, 402). The TCu-380A is now the most widely available IUD, distributed in more than 70 countries (626). Some other donor agencies provide the Nova T and Multiloads as well as the TCu-380A.