Impact of kangaroo care on circadian rhythm, growth, physiological stability in premature infants, and cortisol and melatonin levels in maternal breast milk: A randomized controlled trial

Purpose: This study aimed to examine the effects of regular kangaroo care (KC) on sleep–wake cycles, growth, physiological stability, and maternal breast milk cortisol and melatonin levels in premature infants. Design: This study was a parallel group, single-blind, pre-test-post-test, randomised controlled trial (RCT). Methods: This randomized controlled study was conducted in a neonatal intensive care unit (NICU) in Türkiye between September 2024 and September 2025 Thirty-six premature infants were randomized to intervention (n = 28) or control (n = 28). Infants in the intervention group received KC for three consecutive days, twice daily (10:00 a.m. and 10:00 p.m.) for 60 min per session. Data were collected using the Infant Information Form, Physiological Parameters Monitoring Chart, and Premature Infant Sleep-Wake Cycles Tracking Chart. Sleep–wake cycles were monitored using a Bispectral Index device. Breast milk cortisol and melatonin levels were measured at baseline and on day three using the competitive ELISA method. The study was registered at ClinicalTrials.gov (NCT06589349). Results: Regular KC had a statistically significant effect on BIS values, heart rate, respiratory rate, oxygen saturation, and body temperature (p < 0.05). No statistically significant effects were observed on infant body weight or on maternal breast milk cortisol and melatonin levels (p > 0.05). Conclusion: The findings indicate that regular KC is associated with improved regulation of the sleep-wake cycle and enhanced physiological stability in premature infants. No significant changes were observed in maternal breast milk cortisol or melatonin levels following KC.