What are the odds of being pregnant if you have sex while taking only placebo pills?

Question

I started my period during week 3 of my pack. During week 4 (while taking my placebo pills) I didn't have my period, but I had sex. What are the odds that I'm pregnant?

Answer 1

The same as when you have sex while taking the active pills. Birth control pills are just as effective during the placebo week as they are at any other time.

Answer 2

As long as you took all the pills in the first three weeks, you shouldn't be pregnant. Some people have really light periods or sometimes none when they are on the pill.