When can you not get pregnant so i can have sex then?

Unreliable: In spite of what anybody else may tell you, the "rhythm method" of birth control, in which people have sex only a few days after the end of menstruation or just before menstruation, is very prone to failure. And frankly, what pair of people in love want this? Talk to your physician about all your options -- this is the 21st century -- and perhaps a spiritual advisor with common sense.