The events that occur at birth to sustain life from the transition of the fetus to the newborn are sudden and dramatic. These changes are largely dependent on the pulmonary circulation. With separation of the placenta, the placental oxygen supply ceases, and the infant must establish pulmonary circulation and efficient oxygen transport. This requires a number of complex changes to occur in the physiological function of the newborn lung. These changes are incompletely understood. However, an enormous growth of knowledge has emerged over the past decade, principally by the advent of cellular and molecular techniques.
The Fetal and Neonatal Pulmonary Circulations: American Heart Association, Monograph Series. Arch Pediatr Adolesc Med. 2000;154(7):752. doi:10.1001/archpedi.154.7.752