The scientific basis of contraception

Abstract For centuries the scientific basis of contraceptive methods has consisted almost entirely in the recognition that the male ejaculate contained a factor essential for fertilization. Methods were therefore evolved for preventing the entrance of semen into the higher levels of the female reproductive tract, principally barriers and spermicides of various kinds. The scientific basis for more effective contraceptive techniques broadened only in the twentieth century with the identification of many of the intricate steps involved in conception. In particular, knowledge of hormonal factors involved in the female sexual cycle has led to the development of highly reliable means of ovulation inhibition. Increased understanding promises to offer many other possibilities for controlled interference at critical stages of reproductive events.