How late should you let your period be until you start to...?

Be concerned about pregnancy? I'm a teenager and my period is five days late.. It's kinda based on my period tracker app on my iPod but I'm still getting really scared. How long should I wait until I should suspect I am?|||It depends on whether you have regular or irregular periods. Minen always worked like clockwork so when I was 2-3 days late I knew I had to buy a pregnancy test. If your periods are irregular then wait and see if you start this month|||Well, you can take a test 4 days before your period is due so if u are concerned take one :) At least put your mind at rest x|||Depends how regular/irregular your cycle is. Mine is very regular so i would take a test or see a doctor if i was even a day late.|||Take a test!