Emergency contraception, or post-coital contraception, sometimes called the ‘morning-after pill’, refers to methods of contraception that can be used to prevent pregnancy in the first few days after intercourse. It is intended for emergency use following unprotected intercourse, contraceptive failure or misuse (such as forgotten pills or torn condoms), rape or coerced sex. Emergency contraception is effective only in the first few days following intercourse, before the ovum is released from the ovary and before the sperm fertilises the ovum. Emergency contraceptive pills cannot interrupt an established pregnancy or harm a developing embryo.
Source: World Health Organization – WHO (2012). Emergency Contraception: Factsheet No 244. Available at: http://www.who.int/mediacentre/factsheets/fs244/en/