Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth control only became available in the 20th century. Some cultures limit or discourage access to birth control because they consider it to be morally, religiously, or politically undesirable. The most effective methods of birth control are sterilization ’by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable birth control.