One is to prevent pregnancy and the second is to prevent sexually transmitted diseases. Obviously, if you don't use them, they won't work. The release of the egg is ovulation. The egg is swept into the funnel-shaped end of the fallopian tube, where fertilization may occur, and is transported to the uterus. If fertilization doesn't occur, the egg degenerates and passes through the uterus with the next menstrual period.
Irregular periods make it difficult to know exactly when ovulation occurs.
It is less likely to occur one to three days after your period, but pregnancies have begun at all stages of the cycle. If you are concerned about the possibility of being pregnant, perform a home pregnancy test. I'm 35 and pregnant. Because I will be 36 when I deliver, amniocentesis is recommended. My husband and I are a little skeptical, since we are healthy and come from large families with no histories of birth defects.