The most obvious way to avoid either becoming pregnant or getting someone pregnant is to abstain from sex. This in essence has been the Christian remedy, and lifelong abstinence is still encouraged among such groups as Catholic priests and nuns. In the past, however, only a few societies have been either willing or able to impose long periods of abstinence upon more than a small minority of their members. Some religious groups such as the Manichaeans, a rival of Christianity, are said to have practiced abstinence, and their ideas had a great influence upon Saint Augustine and early Christians. In American history, the Shakers, a religious sect, took a vow of celibacy and abstinence. A small number of Shakers still exist as of this writing, but they were a much larger group in the nineteenth century. They kept their membership by proselytizing and by adopting unwanted children, many of whom elected to take a vow of abstinence when they reached adulthood. Many societies, on the other hand, have adopted periods of abstinence by imposing prohibitions on sexual intercourse during certain times of the year, such as Lent and various feast days, or during certain periods of a woman’s life, such as when a woman is lactating or menstruating. It is highly unlikely that such prohibitions originally were established as birth control measures, although they undoubtedly helped to cut down the pregnancy rate. The belief that women had certain phases of their menstrual cycles when they were unlikely to get pregnant was widespread, although the necessary physiological data to calculate such periods was unknown until the twentieth century. Still, the belief entailed regular periods of abstinence.
Some religious groups have imposed vows of abstinence and celibacy upon a certain segment of their membership. In the case of the Catholic Church this was priests, monks, and nuns, those who enter religious orders or are ordained as priests. Again, this was not done as a means of birth control, but the result nonetheless was that of birth control because a significant number of individuals remained childless, in some periods as many as 10 percent of the population.
Many societies have encouraged adolescents, particularly females, to be abstinent until they were married, but few societies attempted to enforce such rules on the males. Instead, as this topic emphasizes, most societies have hunted for various formulas to curtail the incidence of pregnancy, more or less admitting that abstinence, although perhaps a worthy goal, is one few can achieve.