Internal medicine or general internal medicine (in Commonwealth nations) is the medical specialty dealing with the prevention, diagnosis, and treatment of internal diseases. Doctors specializing in internal medicine are called internists, or physicians (without a modifier) in Commonwealth nations. Internists are skilled in the management of patients who have undifferentiated or multi-system disease processes. Internists care for hospitalized and ambulatory patients and may play a major role in teaching and research. Internal medicine and family medicine are often confused as equivalent in the Commonwealth nations (see below).
Neonatology or neonatology is a subspecialty of pediatrics that includes the medical care of a newborn, especially a sick or premature baby. It is a hospital-based specialty, usually practiced in neonatal intensive care units (NICUs). The main patients of a neonatologist are newborns who are ill or need special medical care due to premature birth, low birth weight, intrauterine growth retardation, congenital anomalies (birth defects), sepsis, lung hypoplasia or asphyxia during Birth.