Breastfeeding and Bottle Feeding: Impact on Preterm Infants' Physiology and Feeding Performance

Inclusion Criteria: * Gestation week at birth determined according to the mother's last menstrual date is 26-31+6 weeks, * Postmenstrual week at the time of the study was 32-36+6 weeks, * Having a body weight of 1500 grams or more at the time of inclusion in the study, * Suggested by the physician to switch to oral nutrition and switched from enteral nutrition to oral nutrition for the first time, * Breastfed, * Preterm infants whose parents' consent was obtained for inclusion in the study and whose parents signed the informed consent form Exclusion Criteria: * Receiving oxygen, * Craniofacial anomalies such as cleft palate, cleft lip, facial muscle paralysis, * Preterm infants with any gastrointestinal, neurological and genetic disease (necrotizing enterocolitis, third and fourth level intracranial hemorrhage, periventricular leukomalacia, hydrocephalus, down syndrome, omphalocele, non-gastrodeia, short bowel syndrome and other diseases)