In 2006, there were nearly 3.5 million hospital discharges among youth aged 1–21 years, equaling 4.0 hospital discharges per 100 children. Hospital discharge rates generally decrease with age until early adolescence, and then begin to increase.
While injuries are the leading cause of death among children and adolescents older than 1 year of age, they were not the most common cause of hospitalization for any age group of children. In 2005-2006, diseases of the respiratory system were the most common cause of hospitalization for children aged 1-4 and 5-9 years, accounting for 39 and 24 percent of discharges, respectively. Mental disorders were the most common cause of hospitalization among children aged 10-14 years, accounting for 24 percent of discharges. Among adolescents and young adults aged 15-19 and 20-21 years, pregnancy and childbirth was the most common cause of hospitalization, accounting for 42 and 64 percent of discharges, respectively.