In 2005, there were 3.5 million hospital discharges among youth aged 1–21 years, or 4.1 hospital discharges per 100 children. This represents little change from 2004. Hospital discharge rates generally decrease with age until about age 9 and then increase during later adolescence.
While injuries are the leading cause of death among children and adolescents older than 1 year, this category accounted for only 9 percent of the hospital discharges of children aged 1–14 years in 2005. Diseases of the respiratory system were the major cause of hospitalization for children 1–9 years of age, accounting for 31 percent of discharges. Pregnancy and childbirth accounted for 65 percent of hospital discharges of young women aged 15–21 years. Mental disorders were the leading cause of hospitalization among youth aged 10–14 years and the second leading cause among 15- to 19- and 20- to 21-year-olds.