The exaxt population of the world is unknown but believed at about 6.2 billion; it continues in its unrelenting growth especially in developing countries. Worldwide famine has been postponed thanks to modern agricultural procedures, known as the Green Revolution, which have greatly increased grain production. Nevertheless, with limited land and resources that can be devoted to food production—and increasing numbers of humans who need both space and food—there appears to be a significant risk of catastrophe by overpopulation. Because of this, there is increased interest in family planning. Family planning in this context means birth control to limit family size.

The subject of "family planning" is not limited to birth control but includes procedures designed to overcome difficulties in becoming pregnant. About 15% of couples are unable to conceive children after a year of sexual activity without using birth control. Many couples feel an intense desire...