The Effect of Inhaling Mother’s Breast Milk Odor on the Behavioral Responses to Pain Caused by Hepatitis B Vaccine in Preterm Infants: A Randomized Clinical Trial

Abstract

Background: Pain control in preterm infants is especially important if the necessary measures are not taken in this regard, the evolutionary process of the brain will be disrupted, and the unrelieved pain can have lifelong consequences. The aim of this study was to compare the effect of maternal breast milk odor (MBMO) with that of another mother’s breast milk odor (BMO) on the behavioral responses to pain caused by hepatitis B vaccine (HBV) injection in preterm infants.Methods: This single-blind randomized clinical trial was performed in the neonatal intensive care unit of Babol Rouhani Hospital, Iran from February 2019 to March 2020. Totally, 90 preterm infants who were to receive the HBV for the first time were randomly selected by random sampling. The neonates were randomly assigned into three groups of (A) MBMO (B) another mother’s BMO and (C) control (distilled water).The data were collected using a questionnaire of demographic characteristics and premature infant pain profile (PIPP). Physiological data were recorded by the pulse oximeter immediately before and after the intervention. The data were analyzed using SPSS18 through chi-square, ANOVA and ANCOVA, and P<0.05 was considered as significant level.Results: Before intervention, there was no significant difference between groups in the mean of heart rate, blood pressure and arterial oxygen saturation (SaO2) percentage (P>0.05). After intervention, there was no significant difference between these A, B and C groups in the mean of systolic blood pressure (70.90±8.29, 70.27±6.70 and 71.77±9.07), diastolic blood pressure (43.63±9.59, 41.77±7.10 and 44.03±10.76) and SaO2 percentage (95.20±5.20, 94.00±6.23 and 91.13±11.78), respectively (P>0.05). However, after intervention, there was a significant difference between groups of A, B and C in the mean of heart rate (146. 6±14.3, 153.70±17.5 and 155.70±17.7), respectively (P=0.01). Moreover, the mean PIPP score was 6.6±1.3, 10 ±2 and 11.4±1.9 in groups A, B and C respectively, so that a significant statistical difference was found between groups (P<0.001). Conclusions: Stimulation with MBMO is effective in reducing the pain of preterm infants, so it can be used in less invasive procedures such as vaccination.Trial registration: IRCT, IRCT20190220042771N1. Registered 18 May 2019- Retrospectively registered, https://en.irct.ir/trial/37646