Effect of Nesting During Intramuscular Injection on Pain, Stress, and Breastfeeding Success in Cesarean-Born Term Newborns

Inclusion Criteria: * Written informed consent was obtained from the parent(s) or legal guardian(s) of the newborn. * Born by cesarean section. * Term newborn (gestational age between 37+0 and 41+6 weeks). * Birth weight between 2,500 g and 4,000 g. * Clinically stable vital signs (including heart rate, respiratory rate, and oxygen saturation). * No acute or chronic medical conditions. * No congenital anomalies. * No requirement for endotracheal intubation, resuscitation, or admission to the neonatal intensive care unit (NICU). * Scheduled to receive the first intramuscular injection after birth. Exclusion Criteria: * Multiple birth (e.g., twins or higher-order multiples). * Administration of vitamin K or hepatitis B vaccine before completion of the study procedures. * Withdrawal of parental consent at any time during the study. * Use of a pacifier, oral sucrose, or any pharmacological or non-pharmacological pain-relief intervention before completion of the outcome assessments. * Discharge from the hospital or transfer to another healthcare facility before completion of the study procedures. * Delayed mother-newborn reunion due to maternal general anesthesia or prolonged sedation following spinal or epidural anesthesia. * Delayed transfer of the newborn to the mother because of prolonged surgery, intraoperative complications, or delayed postoperative stabilization.