What should you do if you start a new pack of birth control late?

If you had unprotected sex and you missed 3 or more pills from a new pack you may want to consider using the Plan B pill. If you have not had sex since missing pills from your new pack - start the new pack as soon as you realize you have missed any and use back up protection (condoms or Today Sponge etc) until you have taken 7 pills in 7 days.

More information at the link.