Study interventions i\] Training: One day before starting the study, mothers in the kangaroo group were informed about kangaroo care. The training was provided in a meeting room outside the NICU. In the training, the advantages of the kangaroo care method for the mother and the baby and how the method will be applied were explained to the mothers. After the PowerPoint presentation, the mothers' questions were answered and they were given a kangaroo care guide prepared by the World Health Organization (WHO) \[19\].The training took about an hour. The researcher who provided the training is experienced in neonatal nursing and has a doctorate in pediatric nursing.

ii\] Preparation of breast milk: The milks that the mothers milked and brought with storage bags were stored frozen below -18 degrees Celsius in the deep freezer of the food preparation room outside the NICU. These frozen milks were warmed by neonatal nurses according to the needs of the baby and given by syringe.

iii\] Kangaroo care: Researchers observed vital signs and oxygen saturation of preterm infants in the kangaroo care group just before and during the kangaroo contact with the mother. After the baby's mother was admitted to the NICU, she was assisted by the researchers for hand hygiene and they went to the incubator together. The mother was seated in a comfortable chair next to the incubator. After the researchers covered the head and back of the preterm baby with a baby blanket, she took it from the incubator and placed it between the mother's breasts, with the head up and upright. The baby was supported not only by the neck and shoulders, but also by the whole body. Skin contact between mother and baby was ensured at the highest level. The baby was positioned so that its lips were touching the mother's nipple. The researchers waited until the baby opened its mouth. The baby's upper and lower lips were placed in such a way that the entire areola was in its mouth. The mother held her breast in a "C" shape with her hand. Thus, the baby's nose was prevented from being blocked. During the application, the researcher gave breast milk in the syringe to the baby through gavage. The babies and their mothers were observed by the researcher throughout the application. Kangaroo care was applied to the infants for 15-20 minutes during feeding, four times a day, five days a week. Kangaroo care of preterm infants fed by gavage continued until they achieved full oral feeding. Kangaroo care was also given to the babies who were connected to the ventilator.

iv\] Standard care: Premature babies in this group were fed by gavage in the incubator. In standard neonatal care, parents could see their babies outside the incubator for 15-20 minutes. If parents want to touch their baby, they can do so through the open windows of the incubator, provided they wash their hands. Babies had only diapers and parents only touched their babies' hands, feet, back and abdomen without skin-to-skin contact. Ventilated premature babies are not placed on their parents' lap in accordance with NICU protocol.

v\] Transition from gavage feeding to full oral feeding: The first feeding of preterm babies is usually made through the orogastric tube due to the incomplete development of sucking and swallowing reflexes and the immaturity of the gastrointestinal tract. Accordingly, premature babies included in the study were fed with an orogastric tube after a certain period of time after their hospitalization. Recordings were made daily and continued until the transition to full oral feeding was achieved.