Why do they recommend that you take this on the first day of your period? Also, in the instruction pamphlet, it says that if you take the pill on the first day of your period, you're protected right away. So day 7 of taking Microgestin Fe 1/20 for the first month I had unprotected sex and he came inside me. I never miss a pill and I take it at the same exact time every day. I want to know my chances of pregnancy? And I also want to know if I should be expecting my period the inactive week right away. How does your body know when to start it's period on birth control?