Hello, and I hope I can help you today. Is extremely unlikely to become pregnant on birth control pills, especially if you extend your cycle by taking the pills longer than necessary rather than missing any. Using birth control pills to suppress your menstrual cycle is medically safe and usually effective. However in some cases you can have what is called breakthrough bleeding where your period can sneak through at the wrong time even though your taking the pills correctly. There are birth control pills that are actually prescribed to make your period, only every three months; these brands basically are just three months of active pills in a row and then taking a placebo week every three months. The issue with suppressing your menstrual cycle with the pill, is that frequently it doesn t work until woman has been on three months cycling for six months to a year. Breakthrough bleeding is the most common side effect that women complain of when being on extended cycle oral contraceptives. So I really do not think you need to worry about having had conceived if you took all your active pills correctly. The best way to stop the bleeding at this point is to stop taking the pill for week... Which will reset your cycle and then you will be able to begin a new pack which will end this particular cycle. Suppressing your menstrual cycle also works best with pills that are the same dose all month long and are not particularly low-dose oral contraceptives. Depending upon your situation, if you decide that you may want to suppress your cycle to avoid menstruation, you might want to discuss the brand of pill you take with your gynecologist and possibly changed to one of the brands of pills that are designed for three months cycling. I hope I was able to adequately answer your question today, and that my advice was helpful. Best wishes, Dr. Brown