Prevention of pregnancy is a fairly recent idea. It allows couples to have fun, but not have children. The voluntary use of contraception has become extremely important because of the world's increasing population. The major cause of this growth is medical care-especially immunizations that protect children against infectious diseases. Sex is one of the strongest forces in interpersonal relationships.
Sex is often part of the cement that holds relationships together.
It is fortunate that people can be sexually active, even if they don't desire children. This is especially true now, when people mature earlier than ever before and live longer, but often don't want to start childbearing until other goals are met. Because sex is such a powerful force, it is used for advertising, and it is subject to abuse. In the past, much of a society's sexuality was regulated by religious institutions. This is still the case in some cultures.