A randomized trial published online in The New England Journal of Medicine suggests that a levonorgestrel 52-mg intrauterine device (IUD) appears to be noninferior to a copper IUD for the purpose of emergency contraception.

In order to evaluate if the levonorgestrel IUD is noninferior to the copper IUD as a form of emergency contraception following unprotected sexual intercourse during the previous 5 days, investigators carried out a trial at six Planned Parenthood health centers in Utah. Pregnancy rates were found to be 0.3% among those who received the levonorgestrel IUD compared to 0% among those in the copper IUD group. The difference was within the noninferiority margin of 2.5% between the two study groups… (Medscape)