Myristic acid in amniotic fluid produces appetitive responses in human newborns

Background: A mixture of eight fatty acids (lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, and linoleic acid) that are contained in human amniotic fluid, colostrum, and milk produces appetitive responses in newborns, suggesting the existence of a transition of sensorial cues that guide newborns to the maternal breast. Objective: To explore the ability of each of these eight fatty acids individually to produce appetitive responses in newborns. Methods: The study included 12 healthy human newborns < 24 h after birth. Using a longitudinal design, cotton swabs that were impregnated with each of the eight fatty acids and control substances (i.e., vehicle, saline, and vanilla) were placed approximately 1 cm from the newborns' nostrils for 30 s. Positive responses that were suggestive of acceptance included appetitive movements (i.e., suckling) and sniffing that were directed toward the cotton swab. Lateral movements of the head away from the swab were considered negative responses. Remaining stationary with no changes in facial expressions was considered indifference. Results: Compared with controls (i.e., vehicle, saline, and vanilla) and the other fatty acids tested, myristic acid produced the longest duration of positive facial responses (suckling and sniffing). No significant differences in negative facial responses were observed in response to the odoriferous stimuli. No reactions that were suggestive of disgust were observed. Conclusion: A complex combination of stimuli, including the odor of myristic acid, may integrate sensory cues that guide newborns to the maternal breast.