Started taking Azithromycin (a macrolide antibiotic) on Friday, December 4th. At the time, I was on my placebo pills for Aviane (I have been on this contraceptive since late June of this year). I began taking my active pills on Monday, December 7th and finished the azithromycin on Tuesday, December 8th. I had unprotected sex (my partner did not ejaculate at all) on Monday, December 21st. I took Plan B that day, as I was advised by both my doctor and a pharmacist that azithromycin could reduce the efficacy of my birth control. What are the chances that I will become pregnant?