dy part or organ system is growing most rapidly both in cell number and size, is known as the critical period of development for that part or system. If an environment factor, such as a chemical or virus, interferes with growth during the critical period, development will be permanently affected. The organ does not have another chance to develop, as the third phase begins at a preset time, even if the developmental potential has not all been achieved. The effects of environmental influences will vary, therefore, in accordance with the stage of prenatal development in which the environmental factor is encountered. During the first three months of pregnancy, tissues and important body systems are beginning to develop in the embryo. Adverse influences during this period will affect the basic structure and form of the body, and many have particularly serious effects on the nervous system. Physical development can be arrested and irreparable malformations may occur. For example, women who took the drug Thalidomide during the first three months of pregnancy gave birth to many children with serious defects, but id did not appear to have adverse effects when taken toward the end of pregnancy.Maternal bondingBelief in the importance of infants early attachment to their mothers was first popularized by Freud’s theory and has been maintained in most later theories. Freud and Erikson both believed that the mother-infant relationship was the prototype for all subsequent relationships. Freud believed that this relationship was established through sucking experiences, whereas Erikson included other aspects of the mother-infant relationship in addition to sucking. Bowlby determined there are five behavioral systems within the infant (following, clinging, crying, smiling, sucking) are focused on the mother and form the basis of the infant’s attachment. Development of each of these response systems depends on both experience and mat...
