See your healthcare provider. Women taking pills note that periods tend to be short and scanty, and you may see no fresh blood at all. A drop of blood, or a brown smudge on your tampon or on your underwear is considered a period when you are on the pill. If you do not have your menstrual period when expected while taking birth control pills, you may want to consult your clinician. If you have not missed any pills and you miss one period without any other signs of pregnancy, pregnancy is very unlikely.
Many women taking birth control pills occasionally miss one period.
Call the clinic if you are worried. You are fairly safe and can start a new package of pills at the regularly scheduled time. If you forget one or more pills and miss a period, you should contact your clinic for a sensitive pregnancy test as soon as possible. If you miss two periods in a row, come to the clinic for a pregnancy test immediately, even if you took your pills everyday. If you do become pregnant while taking birth control pills, you must decide whether you want to have a child at this time or, alternatively, whether abortion is an option for you.