the risk of pregnancy in using routine antibiotics and birth control pills (bcps) is very low. in fact antifungals (e. g. ketoconazole) or macrolide antibiotics (e. g. erythromycin azythromycin biaxin) actually increased blood levels of estradiol--not decrease them. being late taking some bcps can also increase [the] risk of pregnancy but the risk is not large unless you entirely miss for two to three days. unprotected sex on active pills does not increase risk unless you had just completely missed several days of active pills. . i would urge you to do a reliable pregnancy test. for the most accurate answer you can do one test on the first day of your next pack. .
while on birth control i took an antibiotic and was late taking birth control pills. could i be pregnant if i had sex?