The induction of labour with prostaglandin F2alpha by intravenous infusion. II. A comparison of fetal and maternal acid-base values with those found in oxytocin induced labour and in spontaneous labour.

Serial determination of fetal and maternal pH, Pco2 and BDECF was performed in 34 cases of labour inductions with intravenously administered prostaglandin F2alpha or oxytocin. These values were compared with those found in ten cases of spontaneous labour. With the exception of eight cases of "high risk pregnancies" all the remaining parturients were healthy and within the 38th to 42nd week of gestation. With regard to the cases of "uncomplicated" pregnancies the general patterns of the acid-base changes were very similar in the three groups. The BDECF values in fetal scalp blood, however, showed a more marked tendency to increase in the group induced with prostaglandin. Further analysis of this group revealed that the rise of BDECF values could be attributed to cases with episodes of uterine hypertonus or signs of uterine incoordination. In the "high risk" pregnancy group the pH values in fetal scalp blood were lower and the BDECF values higher than in the group of "normal" pregnancy cases. The general pattern and the magnitude of the acid-base changes do not seem to be influenced by the administration of oxytocin or prostaglandin F2alpha as induction agents providing uterine activity is normal. Abnormal uterine activity, initiated by any of the two induction agents, is, however, associated with an increased risk of fetal acidosis.