Effect of kangaroo care on circadian rhythm, growth and physiological parameters and breast milk cortisol and melatonin levels of newborn: A randomized controlled study

The study was conducted to determine the effect of regular kangaroo care on the circadian rhythm, growth, and physiological parameters of premature infants in the neonatal intensive care unit, as well as on maternal breast milk cortisol and melatonin levels. This study, which was conducted in a parallel group, single-blind, pre-test-post-test, randomized controlled experimental design, was carried out in the neonatal intensive care unit of Konya City Hospital. The research was conducted between September 2024 and September 2025. Research data were collected from 56 premature infants. Premature infants were randomly assigned to the intervention (n=18) and control (n=18) groups. The "Infant Information Form," "Newborn Physiological Parameters and Growth Monitoring Chart," and "BIS Monitoring Chart" were used as data collection tools. Premature infants in the intervention group received kangaroo care regularly for three days, 60 minutes during the day (10:00 a.m.) and evening (10:00 p.m.). The control group received care according to clinical routine. Data on the sleep-wake cycle of premature infants were monitored for three days during the day and night using a Bispectral Index device. Breast milk samples were collected before starting the study and at the end of the study on the third day. Descriptive statistics, Independent Sample t Test, Chi-Square, Mixed Design ANOVA analysis, and eta-squared were used to evaluate effect sizes in the analysis of the data. A significance level of p<0.05 was accepted. Ethical committee and institutional approval were obtained, a protocol registration (Clinical Trial No: NCT06589349) was made. In the study, There were statistically significant effect of regular kangaroo care on BIS values (F=36.972 p<0.001 η2=0.406), heart rate (F=17.167 p<0.001 η2=0.241), respiratory rate (F=23.950 p<0. 001, η² = 0.307), oxygen saturation (F = 5.513, p <0.001, η² = 0.093), and body temperature (F = 6.676, p < 0.001, η² = 0.110). There were no statistically significant effect of kangaroo care on the body weight of infants (F=0.621, p=0.539, η²=0.011) or on maternal breast milk cortisol (F=0.005, p=0.942, η²=0.000) and melatonin (F=0.052, p=0.821, η²=0.001) levels did not change. Research results revealed that regular kangaroo care supports the development of circadian rhythms in premature infants by regulating the sleep-wake cycle. Furthermore, the intervention was found to contribute to physiological stability. It was determined that mothers' milk cortisol and melatonin levels did not show any significant change with kangaroo care. Therefore, regular kangaroo care for premature infants in neonatal intensive care units is important for supporting the development of circadian rhythms and maintaining the stability of physiological parameters.