The psychosomatic, especially the hormonal aspects of motherliness are discussed to demonstrate the mother's biological need for continuation of symbiosis in the puerperium and during the child's infancy. This instinctual tendency

toward motherliness corresponds to the helplessness of the newborn; it is gratified by sundry intimate functions of motherhood which supply both mother and infant with the gratification of their dependent needs. Motherliness, developing through sublimation of instinctual impulses, enlarges the span of the mother's personality to encompass her child. The physiological and mental apparatus of the infant forms a system which communicates broadly and fluently with the system of the mother.

The psychology of pregnancy can be understood in the light of the psychodynamic processes which accompany the progestin phase of the menstrual cycle.