In the US, only two emergency contraceptive methods have been FDA approved: oral levonorgestrel and oral ulipristal acetate. However, the copper IUD appears to be an order of magnitude more effective than the approved methods and so copper IUD is often used. But women prefer the levonorgestrel IUD. This study looked to compare the two IUDs as emergency contraceptives. Among 711 women randomized to copper versus levonorgestrel IUDs, pregnancy rates were 1 in 317 in the levonorgestrel group and 0 in 321, equating to non-inferiority for the levonorgestrel IUD.