Just been reading some info about the MAP and came across this...
It's believed Levonelle works by:
preventing your ovaries from releasing an egg altering the lining of the womb, so a fertilised egg can't embed itself there. In Britain and many western countries it is regarded as an emergency contraceptive, not an abortion-causing drug - it won't work if you are already pregnant.
Are you not 'pregnant' from when the egg is fertalised, or is it from being embedded?