Infantile respiratory distress syndrome (IRDS), also called respiratory distress syndrome of newborn, or increasingly surfactant deficiency disorder (SDD), and previously called hyaline membrane disease (HMD), is a syndrome in premature infants caused by developmental insufficiency of pulmonary surfactant production and structural immaturity in the lungs. It can also be a consequence of neonatal infection and can result from a genetic problem with the production of surfactant-associated proteins. IRDS affects about 1% of newborns and is the leading cause of death in preterm infants. Notably, data has shown the choice of elective caesarean sections to strikingly increase the incidence of respiratory distress in term infants; dating back to 1995, the UK first documented 2,000 annual caesarean section births requiring neonatal admission for respiratory distress.The incidence decreases with advancing gestational age, from about 50% in babies born at 26–28 weeks to about 25% at 30–31 weeks. The syndrome is more frequent in males, Caucasians, infants of diabetic mothers and the second-born of premature twins.IRDS is distinct from pulmonary hypoplasia, another leading cause of neonatal death that involves respiratory distress.