In large studies fewer than one woman per 100 became pregnant in the first year of use and, in the longest comparative study, only 2.1 per 100 became pregnant in 10 years of use. Because modern IUDs prevent pregnancy so effectively, they avert many maternal deaths. Thus IUDs rank among the best family planning methods for protecting women's lives. Clearer Understanding Updates Guidance Recent research has helped to lift a cloud that hung over the IUD in the 1980s. Also, there appears to be virtually no increased risk of infertility for a woman using a copper IUD who has a mutually monogamous relationship and thus is not exposed to STDs.
Recent research suggests that IUDs work by preventing sperm and egg from joining.
Evidence shows that copper and all-plastic IUDs help protect against ectopic pregnancy while in use. Better scientific understanding has enabled experts to recommend updated guidance for providing IUDs. These recommendations eliminate unscientific limits on IUD use and better define who can use IUDs safely. IUDs should be inserted only where infection-prevention procedures can be followed. Only one follow-up visit is necessary three to six weeks after insertion to check for infection and expulsion.