Crosscultural ideas about conception and the respective contribution of mother and father to prenatal formation reflect a variety of beliefs which affect the dating of fetus/baby's attainment of human status, and hence rulings about abortion, still-birth burial and infant rearing practices. Concepts about development of the fertilized ovum into a human being by no means follow a linear pattern of growth. While many cultures recognize a continuum from conception to birth, some, like English common law, hold that life begins not at conception but at quickening. Generally, in cultures where sociocultural patterns do not induce parents to discriminate strongly between the sexes and men are nurturant, prenatal sex preferences will reflect personal desires rather than social values. It may be helpful to highlight an underlying unconscious paradigm or pattern for mother-fetus interaction which appears to serve as a basis for much maternal fantasy production - that of the umbilical exchange.