ABSTRACT
N THE TERM infant there is a transition of breathing from episotic irregular, ineffectual movements to regular, rhythmic and effectual effort which is completed by the end of the first week of life. Respiratory rate, at seven days of age, will then show a response, increasing as does the adult response to hypoxaemia (low oxygen levels in the blood). Thus the main adaptation to air breathing has occurred at the end of week one. The respiratory system then grows and matures until eight years of age when the respiratory tree is completed. After this age environmental effects and changes in other body systems, especially those affected by sex hormones, may affect an individual child’s respiratory function.
