Non-Nutritive Sucking vs Non-Nutritive Sucking Combined With Breast Milk on the Neonatal Comfort

Inclusion Criteria: * The preterm infants whose parents agree to participate in the research and sign the informed consent form; * Who have no congenital anomaly; * Who have no chronic disease; * Who have undergone no surgical procedure; * Who have no neurological symptoms; * Who have no NEC (necrotizing enterocolitis) diagnosis; * Who are not sedated; * Who are not hypoglycemic; * Who have been administered no pharmacological analgesic method 4 hours before; * Who are born between ≥28 and ≤36+6 gestation weeks, or are in between ≥28 and ≤36+6 gestation weeks during the procedure. Exclusion Criteria: * The infants whose parents do not agree to participate in the research and do not sign the informed consent form; * Who have a congenital anomaly; * Who have a chronic disease; * Who had undergone a surgical procedure; * Who have neurological symptoms; * Who have NEC (necrotizing enterocolitis) diagnosis; * Who are sedated; * Who are hypoglycemic; * Who have been administered no pharmacological analgesic method 4 hours prior; * Who were between \<28 and \>36+6 gestation weeks.