Determination of pH or lactate in fetal scalp blood in management of intrapartum fetal distress:: randomised controlled multicentre trial

Objective To examine the effectiveness of pH analysis of fetal scalp blood compared with lactate analysis in identifying hypoxia in labour to prevent acidaemia at birth. Design Randomised controlled multicentre trial. Setting Labour wards. Participants Women with a singleton pregnancy, cephalic presentation, gestational age >= 34 weeks, and clinical indication for fetal scalp blood sampling. Interventions Standard pH analysis (n=1496) or lactate analysis (n=1496) with an electrochemical microvolume (5 mu l) test strip device. The cut-off levels for intervention were pH < 7.21 and lactate > 4.8 mmol/l, respectively. Main outcome measure Metabolic acidaemia (pH < 7.05 and base deficit > 12 mmol/l) or pH < 7.00 in cord artery blood. Results Metabolic acidaemia occurred in 3.2% in the lactate group and in 3.6% in the pH group (relative risk 0.91, 95% confidence interval 0.61 to 1.36). pH <7.00 occurred in 1.5% in the lactate group and in 1.8% in the pH group (0.84, 0.47 to 1.50). There was no significant difference in Apgar scores < 7 at 5 minutes (1.15, 0.76 to 1.75) or operative deliveries for fetal distress (1.02, 0.93 to 1.11). Conclusion There were no significant differences in rate of acidaemia at birth after use of lactate analysis or pH analysis of fetal scalp blood samples to determine hypoxia during labour.