Stop taking your birth control pills if you think you are pregnant. Please go see a doctor right away and find out if you are pregnant or not. You do not want to be taking hormonesif there is a 0 fetus developing.
If you've gotten a positive hpt, then stop your birth control immediately.
If you have a negative hpt, why do you think you might be pg while on birth control? Have you missed a period?
I'm not sure how birth control might effect a fetus, but your question will probably be better and more promptly answered in the Women's Health Forum. This is the Men's side; we don't know much about birth control (your question is proof of that).
this is the sexuality and relationhships forum. you must have switched and forgot lol. anyway is your question meaning you are on bc and think you might be pg? you dont want to take it if you are and id call your dr right away to get tested.