A study conducted by the National Research Institute for Family Planning in Beijing, China shows that a copper intrauterine device, or IUD, is 100 percent effective at preventing pregnancy when implanted up to 5 days after unprotected sex. IUDs are one of the most effective forms of long-term contraception, and evidence from smaller studies suggested that it may be effective as an emergency contraceptive. Although it may not be an accessible solution for many women, as it must be inserted by a doctor, this latest study represents another option for women seeking short-term and long-term reproductive options.