Objective: To study the effect of milk odor on nonnutritive sucking by premature newborns.
Design: Blinded, crossover study of the effects of milk vs sham odor on nonnutritive sucking.
Setting: Urban neonatal intensive care unit.
Patients: Twenty-nine premature newborns with gestational age of 29 to 36 weeks.
Intervention: Fourteen subjects were tested with fortified breast milk odor (group 1) and 15 were tested with formula odor (group 2). For the test observation, milk odor was directed to the nose (orthonasal exposure) using a specially modified pacifier. For the control observation, water was used as a sham odor. Observations were made concurrently with tube feeding of the newborn with either fortified breast milk (group 1) or formula (group 2).
Main outcome measures: Total number of sucks and sucking bursts, measured from a digital record of pressure changes within the pacifier.
Results: Nutrient odor increased suck bursts in group 1 subjects, with borderline statistical significance (46.6 bursts/10 min with odor [95% confidence interval (CI), 39-54] vs 35.4 bursts/10 min without odor [95% CI, 28-43]). Unexpectedly, when test and control observations were combined, subjects in group 1 showed an overall increase in number of sucks (260.4 [95% CI, 206-315]) and suck bursts (41.0 [95% CI, 36-46]) compared with group 2 subjects (144.8 [95% CI, 87-203] vs 27.4 [95% CI, 21-34]).
Conclusions: Nutrient odor exposure via pacifier may stimulate nonnutritive sucking during gavage feeding of premature newborns. Further studies on the effects of nutrient odor on nonnutritive sucking by premature newborns must take into account the effects of nutrients given via gavage.