Umbilical cord blood acid-base values in uncomplicated term vaginal breech deliveries

Background. This prospective study was conducted to compare the umbilical cord blood acid-base values of uncomplicated, assisted, vaginal-breech-delivery term neonates with those of uncomplicated, cephalic-vaginal delivery term neonates and to determine whether a different metabolic status should be expected in neonates born by way of uncomplicated vaginal breech delivery. Methods. Umbilical cord artery and vein blood samples were obtained from 30 term neonates with frank or complete breech presentations who were born by uncomplicated assisted vaginal breech delivery. All these neonates had an Apgar score of >7 at 5 min and an uneventful neonatal course (study group). For each neonate in the study group the two consecutive term neonates who were delivered by uncomplicated cephalic spontaneous vaginal delivery, and had uneventful neonatal courses, served as controls (control group). Results. The umbilical cord artery blood pH and pO(2) were significantly lower (p<0.001 and <0.01, respectively) and the pCO(2) was significantly higher (p<0.001) in newborns of the study group, compared to the controls. The umbilical cord vein blood pH was significantly lower (p<0.01), and the pCO(2) significantly higher (p<0.01) in the study group. Conclusions. The umbilical cord blood acid-base values of uncomplicated, vaginal-breech-delivery term neonates differ significantly from those of uncomplicated, cephalic-vaginal delivery neonates. These differences may represent a greater degree of acute cord compression that reflects the different mechanisms of labor in vaginal breech delivery.