Environmental stress and salivary cortisol levels in preterm infants

Area of Science:

• Neonatalogy
• Pediatric Endocrinology
• Stress Physiology

Background:

• Preterm infants experience significant environmental stressors in the Neonatal Intensive Care Unit (NICU).
• Assessing infant stress is crucial for optimizing care and developmental outcomes.
• Salivary cortisol is a biomarker for physiological stress response.

Purpose of the Study:

• To investigate the correlation between salivary cortisol levels and Neonatal Infant Stressor Scale (NISS) scores in preterm infants during their first week of life.
• To analyze changes in NISS scores and cortisol levels over the first week.
• To determine if cortisol levels are associated with gestational age.

Main Methods:

• Included 38 preterm infants (birth weight <1250g and/or gestational age <29 weeks).
• Collected saliva samples on days 0-3 (early) and 4-7 (late) for cortisol measurement.
• Assessed NISS scores retrospectively for the six hours prior to each saliva collection.

Main Results:

• No significant correlation was found between NISS scores and salivary cortisol levels.
• Infants born at <28 weeks gestation exhibited higher median cortisol levels compared to those born at >28 weeks (p=0.0068).
• A significant inverse relationship was observed between NISS scores and gestational age (p=0.04).

Conclusions:

• Elevated cortisol levels in extremely preterm infants (<28 weeks gestation) are not directly correlated with NISS scores.
• NISS scores are inversely related to gestational age, suggesting greater exposure to medical interventions in smaller infants.
• These findings highlight the complex stress response in preterm neonates and the need for individualized care strategies.