In Freudian psychoanalysis, the term oral stage denotes the first psychosexual development stage wherein the mouth of the infant is his or her primary erogenous zone. Spanning the life period from birth to the age of 18 months, the oral stage is the first of the five Freudian psychosexual development stages: (i) the oral, (ii) the anal, (iii) the phallic, (iv) the latent, and (v) the genital. Moreover, because it is the infant’s first human relationship — biological (nutritive) and psychological (emotional) — its duration depends upon the child-rearing mores of the mother’s society. Sociologically speaking, the duration of infantile nursing is determined normatively; in some societies it is common for a child to be nursed by its mother for several years but in others this period is much shorter.
Psychologically, Sigmund Freud (1856–1939) proposed that if the nursing child’s appetite were thwarted during any libidinal development stage, the anxiety would persist into adulthood as a neurosis (functional mental disorder). Therefore, an infantile oral fixation (oral craving) would be manifest as an obsession with oral stimulation; yet, if weaned either too early or too late, the infant might fail to resolve the emotional conflicts of the oral, first stage of psychosexual development and he or she might develop a maladaptive oral fixation.