Five-Year Follow-Up of Effects of Neonatal Intensive Care and Morphine Infusion during Mechanical Ventilation on Diurnal Cortisol Rhythm

Objective: To test the hypothesis that the diurnal cortisol secretion rhythm of children who as neonates had been hospitalized differs from that of children without a history of neonatal hospital admission and that this rhythm differs between these hospitalized children treated with either continuous morphine infusion or placebo. Study design: A follow-up cohort study was performed with 5-year-old children who as neonates participated in a randomized controlled trial of continuous morphine infusion (born 24-42 weeks' gestation), and a control group of healthy term born (≥37 weeks' gestation) children. Five saliva samples over a school day were assayed for cortisol concentrations. The diurnal cortisol rhythm was analyzed with random regression analysis for repeated measurements. Results: Compared with the healthy controls, the trial participants had greater cortisol levels (P = .002) after adjustment for sex and socioeconomic status. The administration of morphine did not affect the cortisol concentrations (P = .66) after adjustment for sex, socioeconomic status, and gestational age at birth. Conclusions: The finding that former trial participants had greater cortisol levels at 5 years of age supports the concept of long-lasting programming of the hypothalamic-pituitary-adrenal axis. Morphine infusion in the neonatal period did not alter cortisol secretion at 5 years of age.

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