title: Developmental change in infants' responses to stress.
abstract: Infant stress responses to a well-baby physical examination and inoculation were observed longitudinally at 2, 4, and 6 months of age. In general, there were cortisol increases over base to the procedures. Cortisol level and cortisol response decreased with age. These data indicate a developmental shift in adrenocortical functioning between 2 and 6 months of age. Further evidence for this shift was seen in the stability of individual responses between 4 and 6 months of age. Individual differences in both cortisol and behavioral responses showed the most stability between these 2 ages. Moreover, diurnal variation in baseline cortisol level was present only at 6 months of age. While a sizable minority of infants showed stress-related cortisol decreases to the procedures at a given age, there was no evidence for cross-age consistency in individual infants showing these cortisol decreases.
authors.affiliation: Department of Pediatrics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick 08903-0019, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lewis
authors.forename: D S
authors.initials: DS
authors.lastname: Ramsay
mesh_terms: D000367:Age Factors; D002657:Child Development; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D007223:Infant; D018730:Infant Behavior; D008137:Longitudinal Studies; D008297:Male; D012463:Saliva / Q000737:chemistry; D013315:Stress, Psychological / Q000523:psychology*
chemical_list: D006854:Hydrocortisone