Birth control and ovulation

Birth control is supposed to help you not get pregnant. Is the high risk of <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">pregnancy tracker</a> for those not on birth control more than those who are?
I feel like even though it's supposed to be a high risk day, wouldn't it kind of be cut in half since you are already taking a form of precaution?