Efficient respiration in a baby relies on adequate anatomical development of the lungs, effective control of respiration, neuromuscular coordination and anatomical and biochemical maturation of the alveoli so that they are stable, thin-walled and in close proximity to the alveolar capillary bed. As well as maturation of lung function, there must also be a major change in pulmonary blood flow at birth to allow perfusion of the capillary bed with deoxygenated blood in order that effective gas exchange can take place. Successful initiation and sustaining of repiration after birth requires all of these things to occur simultaneously otherwise respiratory failure will ensue.