Altered basal cortisol levels at 3, 6, 8 and 18 months in infants born at extremely low gestational age.
OBJECTIVE
Little is known about the developmental trajectory of cortisol levels in preterm infants after hospital discharge.


METHODS
In a cohort of 225 infants (gestational age at birth <33 weeks) basal salivary cortisol levels were compared in infants born at extremely low gestational age (ELGA, 23-28 weeks), very low gestational age (29-32 weeks), and term (37-42 weeks) at 3, 6, 8, and 18 months corrected age (CA). Infants with major neurosensory or motor impairment were excluded.


RESULTS
At 3 months CA, salivary cortisol levels were lower in both preterm groups compared with the term infants (P = .003). Conversely, at 8 and 18 months CA, the ELGA infants had significantly higher basal cortisol levels than the very low gestational age and term infants (P = .016 and P = .006, respectively).


CONCLUSIONS
In ELGA infants, the shift from low basal cortisol levels at 3 months to significantly high levels at 8 and 18 months CA suggests long-term "resetting" of endocrine stress systems. Multiple factors may contribute to these higher cortisol levels in the ELGA infants, including physiological immaturity at birth, cumulative stress related to multiple procedures, and mechanical ventilation during lengthy hospitalization. Prolonged elevation of the cortisol "set-point" may have negative implications for neurodevelopment and later health.
Grunau
Ruth E
RE
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada. rgrunau@cw.bc.ca
Haley
David W
DW
Whitfield
Michael F
MF
Weinberg
Joanne
J
Yu
Wayne
W
Thiessen
Paul
P
D000367:Age Factors; D001034:Apgar Score; D016022:Case-Control Studies; D002657:Child Development / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000378:metabolism*; D007223:Infant; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D007363:Intensive Care Units, Neonatal; D008297:Male; D011336:Probability; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D047929:Term Birth; D013997:Time Factors
D006854:Hydrocortisone