Study aim: Determining the Effect of Oral Calcium Gluconate on Serum Bilirubin Levels in Late Preterm Neonates Admitted to the Neonatal Intensive Care Unit of Valiasr Hospital Design: This study will be conducted as a single-blind, randomized, parallel-group clinical trial on 62 neonates (31 neonates in each of the intervention and control groups). Randomization will be performed using the Block Randomization method. Settings and conduct: This study will be conducted on late preterm neonates admitted to the Neonatal Intensive Care Unit as a single-blind trial (with blinding of the researchers responsible for data analysis) involving 62 neonates (31 neonates in each group). the intervention group will receive oral calcium gluconate in addition to standard phototherapy. Participants/Inclusion and exclusion criteria: Inclusion Criteria: Late preterm neonates with a gestational age of 34 to 36 weeks and 6 days who have indirect (unconjugated) hyperbilirubinemia and are admitted to the Neonatal Intensive Care Unit of Valiasr Hospital. Exclusion Criteria: Neonates who do not meet the inclusion criteria. In addition, any neonate who develops complications during the study will be withdrawn from the study. Intervention groups: All neonates enrolled in the study will receive standard phototherapy according to the hospital protocols under the supervision of a neonatologist. In addition to standard phototherapy, oral calcium gluconate will be administered at a dose of 50 mg/kg of body weight per day, divided into four equal doses (every 6 hours). The calcium gluconate ampoules will be prepared as a solution by the investigator and provided to the nursing staff for the purpose of this study. Administration will continue until the resolution of jaundice and discontinuation of phototherapy. Main outcome variables: Serum indirect bilirubin level, Serum calcium level, Duration of phototherapy