If you're taking an antibiotic and also on the placebo week of your birth control pill will that affect you getting pregnant?

No. : Your placebo week you are protected regardless of your other medications as long as you've been good about taking your pills the rest of the month.

Possibly: Antibiotics can interfere with the hormones in pills and result in accidental pregnancy, but placebo pills have no hormones in them. To be safe, though, since some antibiotics stay in the body for several days after you finish them, i would advise using a condom for backup the entire time you're taking antibiotics and for a week after, even if you start your antibiotics while on placebo pills..