The process of preventing pregnancy. Can be temporary (e.g., birth control) or permanent (e.g., vasectomy or tubal ligation). The three types of temporary contraception are: 1) prevention of sperm from entering the uterus (e.g., condom, diaphragm); 2) ovulation prevention (e.g., hormones); and 3) implantation prevention of a fertilized egg (e.g., intrauterine device). Abortive agents are not contraceptive.