Pusan National University Children’s Hospital (PNUCH) opened in November 2008 as the second National Children’s Hospital in Korea and celebrated its 10th anniversary in 2018. In the last decade, birth rates and pediatric populations have been declining sharply and has been more serious in Busan, Ulsan, and Gyeongsangnam-do where the PNUCH is located, affecting the prevalence of index diseases. The number of the index diseases was investigated by year according to changes in the population. Patients who underwent surgery at PNUCH for 10 years were included. Changes in pediatric population and the number of live births were analyzed using the data from Statistics Korea. The number of the index diseases was analyzed retrospectively through the review of electronic medical records. Statistical analysis was performed through Poisson regression. The number of live births and pediatric population decreased from 69,528 to 48,600 (30.1%) and 1,880,284 to 1,444,961 (23.2%), respectively. Operations of pediatric surgery decreased by 32.3% compared to that during the peak season, but the prevalence rate ratio of the pediatric population increased to 1.03 (<i>P</i><0.001). The number of emergency operation increased due to the largest surge in acute appendicitis operations. Both esophageal atresia and Hirschsprung disease decreased, while hypertrophic pyloric stenosis significantly increased. The absolute number of pediatric surgery cases decreased. However, considering the changes in pediatric population and the number of live births, the relative number of pediatric surgery cases does not changed. The decrease in the number of each disease would be related to the decrease in pediatric population and the number of live births. We should consider the increase of emergency operations such as acute appendicitis.