The Analgesic Effect of Breast Milk

As summarized by Shah in a recent Cochrane Review ¹ “Pain in the neonate,” especially if it is cumulative, “is associated with acute behavioral and physiological changes, and long term morbidities, including adverse neurodevelopmental outcomes.” Thus the interest and challenge in finding nonpharmacological measures (such as holding, swaddling. breastfeeding, sucrose ingestion, music, etc.) that can be incorporated into the care of newborns. This includes those who are undergoing seemingly minimal painful procedures such as diagnostic heel sticks in term infants, or more invasive procedures such as tracheal suctioning in ventilated preterm infants. ²

Repeated studies have documented that breastfeeding is the most potent analgesic procedure, even more than the feeding of breast milk per se. This is not surprising, as the act of breastfeeding, given the actual physical contact of the nursing mother and her infant, is a “multisensory intervention process” ³ , involving the stimulation of the infant’s olfactory, taste, tactile, and auditory systems. Which of these sensory modalities is the dominant or more powerful one is not just a theoretical question, but is critical in decisions as to how to minimize pain in those newborns whose clinical condition precludes nursing and even feeding of pumped milk.

Thus, the importance of the study of Deniz in this month’s issue of Breastfeeding Medicine, wherein the effect of exposing infants to mother’s own breast milk odor is documented as a pain and stress-reducing procedure. This study adds to previous reports that indicated that breast milk odor is a powerful analgesic modality. ⁴ However, given the methodological limitations and inadequacies of many of these studies, to date there is still no consensus as to what is the most effective analgesic modality to be used when the care of the infant entails pain and stress.

Thus, It is clear that there is no justification to continue to study the effect of “x” analgesic modality compared to a control group that does not receive any analgesics. Such studies that continue to inflict pain on the “control” newborn without providing even one of the proven analgesic, care procedures are simply unethical. What is needed are comparative efficacy studies not untreated controls.!

That the olfactory system is such a powerful sensory modality has been repeatedly demonstrated, as smell is not dependent on cognitive cortical function. As such, both the newborn whose subcortical rhinencephalon system is intact and the mother whose cortical cognitive function is in a degree of disarray in the immediate postpartum period can respond to smells. ⁵ Thus the mother can rely on smell to identify her own infant and begin to establish a degree of attachment.^6,7 The infant in turn can benefit from the odor of its mother’s milk as it is self “medicated” and can thus adjust to the vagaries, trials, and discomforts of extrauterine life. Yes, breastfeeding is the ultimate!