While the psychological world that the newborn confronts is complicated they possess a biological predisposition to create a sense of who they are or, as psychologists term it, a "sense of self" from the social experiences they encounter. Beginning in their second year a profound continuing struggle exists between infant and caretaker as the child battles to establish their autonomy apart from the people who controls their destiny. But because babies are not born with instructions and parents have their own childhood-based limitations, the "good-enough" parent-child interaction needed by a child is not always gained, to the long-term suffering of both. Which is where psychotherapy may enter their lives but that is another matter.
A Psychologist's Thoughts on Clinical Practice, Behavior, and Life
While a child's birth is joyously anticipated, their parents' initial reaction is stress. This, even with a child who is generally considered easy to parent since this pain is both universal and unavoidable.
Beginning at birth, a newborn makes unceasing demands of their parents to become a more effective caretaker. Demands that are critical since a child is dependent on their parents for survival. But the adult mind is conservative and resists the rapid personality change that is needed. This clashing of demands and wills creates parental stress but, slowly, a melding of the needs of both.
An added stress is that a newborn is inserted into an ongoing (family) social system that has developed over time, and must now transform itself to incorporate this unselected newcomer.