title: The effects of birth condition on infants' cortisol response to stress.
abstract: OBJECTIVE, DESIGN, AND SUBJECTS: To examine the effects of nonoptimal birth condition on cortisol response to routine inoculation in a longitudinal sample of full-term healthy infants at 2, 4, and 6 months of age.
  
  
  RESULTS
  Optimal versus non-optimal birth condition was defined by a large versus small head circumference and a high versus low 1-minute Apgar score. An optimal birth condition was associated with a high cortisol response at 2 months, but a low cortisol response by 6 months of age.
  
  
  CONCLUSIONS
  The findings indicate a reversal in the meaning of high adrenocortical reactivity between 2 and 6 months of age: high cortisol response may index optimal functioning at 2 months, but nonoptimal functioning by 6 months of age. Together with other results, this reversal provides evidence for a developmental shift in adrenocortical functioning during this period. The findings also show that the effects of a nonoptimal birth condition in otherwise healthy full-term infants persist for at least the first 6 months of life.
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: D S
authors.initials: DS
authors.lastname: Ramsay
authors.forename: M
authors.initials: M
authors.lastname: Lewis
mesh_terms: D000704:Analysis of Variance; D001034:Apgar Score; D001724:Birth Weight; D002508:Cephalometry; D036861:Delivery, Obstetric; D005260:Female; D005865:Gestational Age; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy; D012463:Saliva / Q000737:chemistry*; D013312:Stress, Physiological / Q000503:physiopathology*
chemical_list: D006854:Hydrocortisone