Effect of Olfactory Stimulation with Breast Milk on Pain Responses to Heel Stick in Premature Infants: A Randomized Controlled Trial

Purpose: This study aimed to evaluate the effect of breast milk olfactory stimulation on pain response in premature infants during heel stick tests. Methods: A quasi-experimental randomized controlled trial was conducted in the neonatal intensive care unit of a tertiary-level hospital in Seoul, Korea. A breast milk group was provided olfactory stimulation with breast milk 30 seconds before the start of heel stick sampling, and a control group underwent heel stick sampling without olfactory stimulation. To evaluate infants' pain response, the heel stick procedure was video recorded, and pain response was assessed separately by two blinded research assistants using the Premature Infant Pain Scale (PIPS) through behavioral response, heart rate on physiological monitoring, and blood oxygen saturation on pulse oximetry through the video recording. Results: Forty-eight premature infants (gestational age, within 28-37 weeks, n = 24; control) were included in this study. The pain scores of the breast milk group were significantly lower than those of the control group (z = -2.04, p = 0.021). Conclusion: Breast milk odor may reduce pain in premature infants during heel stick tests.