The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis

Abstract Background Effective management of neonatal pain and stress is crucial, with non-pharmacological approaches like maternal odor showing promise. However, mixed evidence exists on its efficacy. This study aims to comprehensively assess the effects of breast milk odor on pain and stress (prima...

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Main Authors: Shahla Shafaati Laleh, Sevil İnal, Mahsa Maghalian, Mojgan Mirghafourvand
Format: Article
Language:English
Published: BMC 2025-02-01
Series:BMC Pediatrics
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Online Access:https://doi.org/10.1186/s12887-025-05504-z
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author Shahla Shafaati Laleh
Sevil İnal
Mahsa Maghalian
Mojgan Mirghafourvand
author_facet Shahla Shafaati Laleh
Sevil İnal
Mahsa Maghalian
Mojgan Mirghafourvand
author_sort Shahla Shafaati Laleh
collection DOAJ
description Abstract Background Effective management of neonatal pain and stress is crucial, with non-pharmacological approaches like maternal odor showing promise. However, mixed evidence exists on its efficacy. This study aims to comprehensively assess the effects of breast milk odor on pain and stress (primary outcomes) and on oxygen saturation (SpO2) and heart rate (secondary outcomes) in neonates. Methods A thorough search was conducted on PubMed, Cochrane, SID, Embase, and Google Scholar until January 14, 2025, without time restrictions. A meta-analysis was performed to compare outcomes between intervention and control groups, assessing heterogeneity using the I2 statistic and chi-squared test. A random effects model was applied for high heterogeneity (I2 ≥ 30%, p < 0.05), analyzing continuous outcomes with mean difference (MD) and standardized mean difference (SMD) at a 95% confidence interval (CI). Subgroup analyses were conducted based on newborn procedures and term status, along with meta-regression and sensitivity analyses. Trial Sequential Analysis (TSA) was employed to ensure reliable conclusions about the intervention effects, and the certainty of evidence was evaluated using GRADE. Results The systematic review included seven studies (RCT and quasi-experimental) revealing that breast milk odor significantly reduces pain responses in neonates (SMD: -1.60, 95% CI: -2.48, -0.72; I2 = 94%; 7 trials; 478 neonates; low-certainty evidence). It also improved key physiological parameters, such as oxygen saturation (MD: 1.64, 95% CI: 0.49, 2.80; I2 = 57%; 5 trials; 288 neonates; very low-certainty evidence) and heart rate (MD: -6.73, 95% CI: -12.33, -1.13; I2 = 78%; 5 trials; 288 neonates; very low-certainty evidence). Although a reduction in stress levels was noted, it did not reach statistical significance (MD: -0.64, 95% CI: -1.87, 0.59; I2 = 89%; 2 trials; 128 neonates; very low-certainty evidence). Meta-regression indicated a significant correlation between cesarean delivery rates and neonatal pain response (p = 0.010). TSA results confirmed the analysis was adequately powered for pain outcome. Conclusion The review underscores the potential of breast milk odor as a non-pharmacological intervention for managing pain in neonates. However, the low to very low certainty of evidence calls for further research to validate these findings and improve neonatal care protocols.
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spelling doaj-art-99d9f3e7c7e34db597d84a92d22814a42025-08-20T02:16:40ZengBMCBMC Pediatrics1471-24312025-02-0125111810.1186/s12887-025-05504-zThe effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysisShahla Shafaati Laleh0Sevil İnal1Mahsa Maghalian2Mojgan Mirghafourvand3Midwifery Department, Faculty of Health Science, Istanbul University - Cerrahpaşa, Postgraduate PhD Program StudentMidwifery Department, Faculty of Health Science, Istanbul University-CerrahpasaDepartment of Midwifery, Faculty of Nursing and Midwifery, Tabriz University of Medical SciencesDepartment of Midwifery, Faculty of Nursing and Midwifery, Tabriz University of Medical SciencesAbstract Background Effective management of neonatal pain and stress is crucial, with non-pharmacological approaches like maternal odor showing promise. However, mixed evidence exists on its efficacy. This study aims to comprehensively assess the effects of breast milk odor on pain and stress (primary outcomes) and on oxygen saturation (SpO2) and heart rate (secondary outcomes) in neonates. Methods A thorough search was conducted on PubMed, Cochrane, SID, Embase, and Google Scholar until January 14, 2025, without time restrictions. A meta-analysis was performed to compare outcomes between intervention and control groups, assessing heterogeneity using the I2 statistic and chi-squared test. A random effects model was applied for high heterogeneity (I2 ≥ 30%, p < 0.05), analyzing continuous outcomes with mean difference (MD) and standardized mean difference (SMD) at a 95% confidence interval (CI). Subgroup analyses were conducted based on newborn procedures and term status, along with meta-regression and sensitivity analyses. Trial Sequential Analysis (TSA) was employed to ensure reliable conclusions about the intervention effects, and the certainty of evidence was evaluated using GRADE. Results The systematic review included seven studies (RCT and quasi-experimental) revealing that breast milk odor significantly reduces pain responses in neonates (SMD: -1.60, 95% CI: -2.48, -0.72; I2 = 94%; 7 trials; 478 neonates; low-certainty evidence). It also improved key physiological parameters, such as oxygen saturation (MD: 1.64, 95% CI: 0.49, 2.80; I2 = 57%; 5 trials; 288 neonates; very low-certainty evidence) and heart rate (MD: -6.73, 95% CI: -12.33, -1.13; I2 = 78%; 5 trials; 288 neonates; very low-certainty evidence). Although a reduction in stress levels was noted, it did not reach statistical significance (MD: -0.64, 95% CI: -1.87, 0.59; I2 = 89%; 2 trials; 128 neonates; very low-certainty evidence). Meta-regression indicated a significant correlation between cesarean delivery rates and neonatal pain response (p = 0.010). TSA results confirmed the analysis was adequately powered for pain outcome. Conclusion The review underscores the potential of breast milk odor as a non-pharmacological intervention for managing pain in neonates. However, the low to very low certainty of evidence calls for further research to validate these findings and improve neonatal care protocols.https://doi.org/10.1186/s12887-025-05504-zOlfactory StimulationMaternal BehaviorNewbornNon-pharmacologicalPainStress
spellingShingle Shahla Shafaati Laleh
Sevil İnal
Mahsa Maghalian
Mojgan Mirghafourvand
The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
BMC Pediatrics
Olfactory Stimulation
Maternal Behavior
Newborn
Non-pharmacological
Pain
Stress
title The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
title_full The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
title_fullStr The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
title_full_unstemmed The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
title_short The effect of breast milk odor on infant pain and stress levels: a systematic review and meta-analysis
title_sort effect of breast milk odor on infant pain and stress levels a systematic review and meta analysis
topic Olfactory Stimulation
Maternal Behavior
Newborn
Non-pharmacological
Pain
Stress
url https://doi.org/10.1186/s12887-025-05504-z
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