Despite advances in prenatal diagnosis and postnatal therapies, including extracorporeal membrane oxygenation (ECMO), inhaled nitric oxide therapy, and ventilator strategies that minimize ventilator-induced lung injury, morbidity and mortality rates for babies with congenital diaphragmatic hernia (CDH) remain high. The survival relates to the degree of prenatal lung compression and the subsequent impairment of pulmonary function following delivery. Prenatal assessment by ultrasound or magnetic resonance imaging allows to estimate the severity by relating the circumference of the lung contralateral to the hernia to the fetal head circumference lung to head ratio (LHR) and by noting the degree of upward herniation of the liver. Based on the observed to expected lung to head ratio (O/E LHR), prenatally diagnosed congenital diaphragmatic hernia can be prognostically assessed. While overall survival of congenital diaphragmatic hernia is approximately 60%, an O/E LHR <25% is associated with survival between 11-24%.