Purpose: This study was carried out to assess the effect of the odor of breast milk and formula milk on reducing the acute pain of newborn infants during the heel-prick blood sampling. Methods: Eighty-four newborn were randomly assigned into two groups (formula milk group and breast milk group) with 42 infant searches. The pain that the newborn felt before, during, and after heel-prick blood sampling was assessed using Neonatal Infant Pain Scale; their heart rate and blood oxygen saturation were measured with a pulse oximeter. Saliva samples were taken from newborns before and after sampling, and their salivary cortisol level was measured. During sampling, the crying duration of newborn was recorded with a chronometer. Results: The pain threshold and heart rates of the newborn in the breast milk group were significantly lower than those in the formula milk group (p < 0.001). Salivary cortisol in the formula milk group increased and oxygen saturation levels in these infants decreased significantly more as compared to the breast milk group (p < 0.05). Conclusions: The odor of breast milk may be helpful in reducing the pain of newborn during heel-prick blood sampling.
Keywords: breast milk; calming effect; pain; term newborn.