How come you don't get pregnant while on the placebo week of pills?

You take 3 weeks of influential pills. Then there's that week of nonactives. Well if you don't bring back your period till wednesday and you've have sex the days before it..how come you don't bring back pregnant? If you miss 1 pill in the third week you can carry pregnant..how come not during the nonactive week?
Answers:

Missed period, brown discharge, i call for advice!?

The placebo pills allow a completely small dip in your hormone height, allowing for a withdrawal bleed. It take that 3 weeks of active pills to find the hormone level lofty enough to allow for the bleeding while still preventing pregnancy.

Is their anyway i can own my period sooner or following?

it's not a placebo...a placebo is when a controled group of people are given apill and they are beneath the immpression that the pill has stirring ingrediants.

the green pills in the Ortho Tricylen pack are "reminder" pills.

don't know the answer to your question though.

Swimming away a grill for ez points?

Because the hormones in the rest of your month's pills stop ovulation. No ovulation=no pregnancy.