How is it possible to get pregnant on the pill?

Ol

Okay so I know the answer to the poll i just did it as a poll so more people would reply lol. I understand how if you don’t use the pill properly you can still ovulate and therefore get pregnant. But if you use the pill with perfect use, don’t forget to take any and use at the same time every day and start again at the right time after your break, why are you only 99.7% safe from pregnancy? Like I just don’t understand it? How is there still a chance you’ll get pregnant without ovulating? Or how is there still a chance you would ovulate with perfect use?

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