Olfactory sensory and perceptual evaluation in newborn infants: A systematic review

Abstract

Fetuses are able to process olfactory stimuli present in the womb and continue to show a preference for these odors for months after birth. Despite the accumulated knowledge about their early ability to perceive odors, there is a lack of validated scales for odor response in newborns. The evaluation of reactions of the olfactory system to environmental stimuli in infants has been defined by methodological theoretical approaches of experimental and clinical assessment tools. These approaches are mainly based on psychophysical approaches and predominantly use behavioral and physiological measures. Examples can be found in studies describing early abilities of newborn babies for behaviors or heart rate variability showing memory of maternal food preferences or mother's breast milk. This systematic review aimed to determine whether validated odor assessment tools can be feasibly used in studies. Particularly in light of the current COVID‐19 pandemic and evidence of associated olfactory impairment resulting from SARS‐COV‐2 infection, the study is also motivated by the need for tools to assess olfactory function in neonates.

Odor hedonic responses in children and young people with profound intellectual and multiple disabilities

“…Five hedonic indicators, i.e., smiles, positive vocalizations, pouts, negative vocalizations, emotional outburst, plus nausea reactions as physical response, were recorded throughout the duration of exposure to the stimuli. The selection of these indicators was based on two rationales: (1) that they have been reported in the developmental literature [( 37 ) for a systematic review] and that they (2) belonged to the register of behaviors of people with PIMD ( 3 , 9 , 38 , 39 ). As a positive hedonic attribution usually induces approach or avoidance behavior ( 5 ), three more indicators were used, namely: head alignment on the stick, nose/hand coordination on the stick and attempts to reject the stick, resulting in nine indicators in total.…”