A pill for emergency contraception. More effective than Plan B, but requires a prescription where Plan B is over the counter. Lke Plan B, Ella must be used before the egg leaves the ovary. It works by delaying ovulation so any sperm that are present in the Fallopian tubes will have at least five days to die before the egg is released. It does not cause an abortion and does not interfere with implantation after conception has occurred. When used correctly has about a 2% failure rate.