First things first: hormonal emergency contraception, also known as the morning after pill, works by delaying ovulation after unprotected sex or contraceptive failure.
As sperm can survive in the womb for up-to five days, you could fall pregnant after unprotected sex even if you ovulate a few days after sex.
The morning after pill can help prevent ovulation, so no egg is released and therefore it cannot merge with the sperm and you cannot get pregnant.
If an egg has already been fertilised before taking the morning after pill, emergency contraception does not cause an abortion.
There are two types of active morning after pill ingredients available in the UK: ulipristal acetate, which is found in emergency contraceptive pill ellaOne, and levonorgestrel.
Ulipristal acetate is the most effective morning after pill ingredient and is 2.5 times more effective than levonorgestrel.**