i got pregnant while on bc, and didn't stop until i was 5 days late. so that would be about 2 weeks of being pregnant and taking the pill. i stopped as soon as i found out. i had no problems at all, he was born at 38 weeks healthy and beautiful. he is now 4 and doing wonderful.
i have never heard of anything negative, i guess it would depend on how long you took it. you should just stop as soon as you find out. if you think you are pregnant, then i would by one of those early test and try to find out as soon as possible. good luck and hope this helps.