Physiology of the neonate

Abstract The neonatal period includes the first 28 days of life. Prematurity is defined as birth before 37 completed weeks of gestation. Extreme prematurity refers to those born before 28 weeks’ gestation. The overall incidence of prematurity is about 11%. Prematurity is the leading cause of neonatal deaths. Antenatal steroids given between 24 hours and 7 days before birth decrease the risk of respiratory distress syndrome. Thermoregulation in the neonate, especially in the premature, is crucial as hypothermia is associated with increased morbidity and mortality. Specific issues pertaining to the neonate in the perioperative period that are usually unrelated to surgery, but influence management, include: meconium aspiration syndrome; respiratory distress in the newborn; apnoea of prematurity; sepsis; patent ductus arteriosus; retinopathy of prematurity; neonatal jaundice; intraventricular haemorrhage; and hypoxic ischaemic encephalopathy. Clinical assessment of the neonate should follow a consistent and standard process, taking care to be gentle, avoid heat loss, disturb the infant as little as possible, and minimize the risk of nosocomial infection.