Chylothorax, defined as effusion of lymph into the pleural cavity, is the most common congenital pleural effusion in neonates.1 2 Advances in prenatal diagnosis, antenatal treatments, and improvements in neonatal intensive care have reduced the rate of perinatal mortality associated with congenital chylothorax.3 The aim of our retrospective study was to identify the risk factors for mortality in infants with congenital idiopathic chylothorax, admitted to neonatal intensive care. We defined congenital idiopathic chylothorax as accumulation of lymphatic fluid in the pleural cavity with a lymphocyte fraction >80%, associated with a negative prenatal diagnostic procedure—that is, the prenatal …