Experience with modern inert IUDs to date: a review and comments

A review of data from various large-scale studies reveals as much variation between studies as between devices. Many factors clearly unrelated to the IUD design undoubtedly influence their efficacy and continued use. Thus, the conclusions of the 1968 FDA report on effectiveness and utility still appear valid at this time. They are: A. "The Committee finds adequate scientific data attesting to the effectiveness and utility of the intrauterine devices." B. "The intrauterine devices are highly effective in preventing pregnancy, although they are not quite as reliable as the hormonal contraceptives if the latter are taken according to instructions." C. "The rate of continuation of use is similar to that of the oral contraceptives and is far higher than that of traditional methods, at least among the socially and economically deprived."