Evaluation of physiological and behavioral responses in newborns preterm infants stimulated with the smell of breast milk

Abstract

Stimulation with maternal odors in the immediate postnatal period is an effective strategy to achieve the continuity of the maternal ecological niche due to prematurity. In the neonate the sense of smell is fine developed, allowing the interaction of the baby with maternal biological odors, establishing a "psychobiological bridge" that could impact on the growth, development and subsequent attachment of the baby. The main goal is to evaluate physiological and behavioral responses in premature infants stimulated with maternal milk odors analyzing  heart rate changes, oxygen and cerebral saturation, and hedonic response to the maternal odors. Furthermore, encourage the use of a non-invasive, ecological  and low cost strategy stimulation strategy that can increase the growth and development of prematures.

Forty preterm infants under 37 weeks, and older than 72 hours of life were stimulated with distilled water and  breast milk using a cotton swab for two minutes. Brain saturation was assessed using infrared spectroscopy (NIRS) and systemic saturation and heart rate with regular monitoring. Also, we use facial filming for analysis of hedonical behavioral responses, two minutes prior to stimulus (basal period), two during stimulation and two post-stimulation.

Taking the average duration of the set of facial behaviors assessed for their appetitive/aversive hedonic value at each presentation of stimulus, a significant increase (p < 0.05) is observed in behaviors considered appetitive when stimulated with milk compared to the stimulation with water. Observing facial behaviors, there is a primacy of sucking behavior over the smell of breast milk (p < 0.05) compared to the other facial behaviors evaluated. Physiologically it is observed a significant difference in brain saturation when the baby is stimulated with milk, compared to stimulation with distilled water. There are no significant differences in heart or respiratory rate.