PURPOSE
The study was done to measure the effects of maternal heart sound on body weight, physiologic reactions (heart rate [HR] and cortisol) and behavioral states of preterm infants.
METHODS
Thirty-five preterm infants were recruited from a neonatal intensive care unit at a university hospital. Institutional Review Board approval and informed consent were obtained. The infants were assigned to an experimental group (n=18) with an auditory stimulation for 7 days of life, a continuous delivery of maternal heart sound using MP3 attached inside the incubator, or to a control (n=17) without any auditory stimulation. The outcome variables, daily variations in weight, HR and behavioral states, and differences in cortisol were analyzed.
RESULTS
There were differences in variations of daily weights (F=3.431, p=.011) and in cortisol (t=3.184, p=.006) between groups, but no difference in variations of daily HR (F=0.331, p=.933) and behavioral states (F=1.842, p=.323).
CONCLUSION
The findings support the safety of continuous maternal heart sound as no changes in HR and behavioral states occurred, and the efficacy as weight increased and cortisol decreased. This auditory simulation may lead to more efficient utilization of energy in preterm infants by consistently providing familiar sounds from intrauterine life and blocking noxious sounds from NICU environments.

Citations

• Effects of Music Intervention Techniques on Very-Low-Birth-Weight Infants in Neonatal Intensive Care Unit: A Preliminary Study
  Ji Yun Yun, Ji Sun Kim, So-Yeon Shim, Su Jin Cho, Eun Ae Park, Hyun Ju Chong
  Neonatal Medicine.2020; 27(4): 174.     CrossRef
• Effects of Hearing Recorded Mother's Voice on Physiological Reactions and Behavioral State of Sleep, Weight of Very Low Birth Weight Infants
  Mi-Hyang Choi, In-Soon Kang, Young-Hae Kim
  Child Health Nursing Research.2014; 20(3): 185.     CrossRef
• Effects of the 'Intervention - Mother's Song' on Physical Response and Behavioral State of Low-Birth Weight Infants in a Neonatal Intensive Care Unit.
  Ji Sun Park, Kyung Ja Hong, Kyung Sook Bang
  Child Health Nursing Research.2013; 19(3): 198.     CrossRef