Gut at Risk: Epithelial nutrient digestion and absorption, protection and defence

The newborn’s transition from intrauterine to extrauterine life is marked by a chain of rapid and complex physiological changes. For example, this adaptive process is characterised by the transition from foetal ‘respiratory’ activity to normal ventilation.1 Onset of respiration stimulates a series of cardiopulmonary changes – e.g. increase in pulmonary blood flow and closure of the foramen ovale and ductus arteriosus – as the newborn makes the transition from foetal to neonatal circulation. Furthermore, in utero, the foetus is dependent on the placenta and swallowed amniotic fluid for its nutrition. Pivotal, too, is the physiological transition that occurs as the foetus, once born, replaces the placenta with his gastrointestinal (GI) tract to obtain nutrition. Enteral feeding, preferably breast milk, is vital for optimal growth and d