About 20 per cent of women how uses the emergency pill, will have an early period and 10 per cent a late one. You should go back to your doctor or the clinic if your period is more than a week late, the bleeding is lighter than usual or the bleeding is on and off, as you might be pregnant.
Hope this answers your question!
REFERENCE(S)
1. Disability Online, 2006.
Contraception - the morning after pill