Intrathoracic pressure and volume changes during the spontaneous onset of respiration in babies born by cesarean section and by vaginal delivery.

We studied the first breath of newborn infants delivered by cesarean section. Inspiratory pressure and volume were found to be similar to those in infants born vaginally. However, the expiratory and delivery pressures were found to be smaller. Functional residual capacity was formed less frequently after cesarean section than in the vaginally delivered group.