Lung volumes and lung mechanics in babies born vaginally and by elective and emergency lower segmental cesarean section

Abstract

DURING PASSAGE down the birth canal, compression of the infant's thoracic cage results in elimination of variable amounts fetal lung liquid. 1 Babies born by cesarean section are not subjected to this squeeze. Two studies have shown that the crying vital capacity is reduced in babies born by cesarean section compared with those born vaginally. 2. 3 Measurement of the thoracic gas volume by Milner et aP using the body plethysmograph has demonstrated a clear-cut difference between the lung volumes of vaginally born babies compared with those born by cesarean section in the first six hours after birth. There was, however, a suggestion that the differences may last only a few hours, although the time course for the resolution of transient tachypnea of the newborn, which is attributed to delayed clearing of lung fluid, is much longer. The present study was undertaken with two aims: (1) To determine for how long these differences in lung volumes and lung mechanics persist. (2) To determine whether the process of labor itself contributes to the clearance of liquid.