Pediatricians are doctors that monitor the physical, behavioral, and mental health of a child. Pediatricians treat patients from birth to around twenty-one. It is around twenty-one because each pediatric office has different policies about how long they will keep a patient; some offices only treat patients until they are eighteen and some until patients are twenty-three. The goal of a pediatrician is to provide medical care to children who are chronically ill and to provide preventative and diagnostic health services to patients. To be a pediatrician, you need to complete three years of a pediatric residency program after medical school. After the residency program a pediatrician is eligible for board certification and the option to specialize in subsections. These subsections include pediatric cardiology, pediatric endocrinology, pediatric gastroenterology, pediatric hematology, neonatal medicine, and pediatric nephrology.