neonatal breathing, respiration in newborns. It begins when pulmonary fluid in the lungs is expelled by compression of the thorax during delivery and resorbed from the alveoli into the bloodstream and lymphatics. As air enters the lungs, the chest and lungs recoil to a resting position, but forceful inspirations are necessary to keep the lungs inflated. Such inspirations are triggered by changes in blood gas tension, a strong Hering-Breuer reflex, decrease in body temperature, and tactile stimuli. Irregular fetal breathing movements, which occur during rapid eye movement sleep, may be observed as early as 13 weeks of gestation. At birth the peripheral and central chemoreceptors involved in the control of respiration rate are very active, and newborns are highly sensitive to carbon dioxide during the first weeks. However, the control of rhythm breathing is not fully developed at birth.
