Neonatology is a subspecialty of Pediatrics that consists of the medical care of new-born infants, especially the ill or premature newborn infant. It is a hospital-based specialty, and is usually practiced in neonatal intensive care units (NICUs). Neonatal infection can be acquired in utero transplacentally, through the birth canal during delivery (intrapartum), and from external sources after birth (postpartum). In utero infection, which can occur any time before birth, results from overt or subclinical maternal infection. Consequences depend on the agent and timing of infection in gestation and include spontaneous abortion, intrauterine growth restriction, premature birth, stillbirth, congenital malformation (e.g., rubella), and symptomatic (e.g., cytomegalovirus [CMV], toxoplasmosis, syphilis) or asymptomatic (e.g., CMV) neonatal infection. Common viral agents include herpes simplex viruses, HIV, CMV, and hepatitis B.