If you are pregnant, then your periods wil cease. The period is the emission of the broken-down uterus wall, which then regrows through the cycle, but the wall ceases to break down once a foetus is conceived - its purpose is to protect the foestus. If you are unsure, contact your GP or Family Planning Clicic for some professional advice.
Hi there, what andy hughes says is usually right, but if you have not taken your pills properly there is a slight chance with some women that the bleed between pill cycles could continue even if you are pregnant. This is rare, but if you are concerned, go see you doctor who can check you over and give you more information.