When a male and a female gets involve in the activity of sexual intercourse, at that time the fluid named semen is released from the penis into the body of female. The semen contains sperms. The sperm travel all the way to reach the fallopian tube and then go and try to penetrate the ovem, present in the fallopian tube. After the sperm penetrate the egg, the fusion of nucleus of egg and sperm takes place, and the cell division starts which forms zygote. This is how a female gets pregnant by the process of fertilization.