Background
Fetal scalp blood sampling for lactate measurement (FBSLM) is sometimes used to assist in identification of the need for expedited birth in the presence of an abnormal cardiotocograph (CTG). However, there is no randomised controlled trial evidence to support this.

Aim
To determine whether adding FBSLM reduces the risk of birth by emergency caesarean section in labours complicated by an abnormal CTG, compared with CTG without FBS.

Material and Methods
Labouring women at a tertiary maternity hospital in Melbourne, Australia with a singleton, cephalic presentation, at ≥37 weeks gestation with an abnormal CTG pattern were randomised to the intervention (n = 61), with intermittent FBSLM in addition to CTG monitoring, or control (CTG without FBS, n = 62). The primary outcome was rate of birth by caesarean section. Secondary outcomes included overall operative birth and fetal and neonatal safety endpoints. Trial registration: ACTRN12611000172909.

Results
The smaller than anticipated sample was unable to demonstrate an effect from adding FBSLM to CTG monitoring on birth by caesarean section vs monitoring by CTG without FBS (25/61 and 28/62 respectively, P = 0.64, risk ratio 0.91, 95% confidence intervals 0.60–1.36). One newborn infant in the CTG group met the criteria for the composite neonatal outcome of death or serious outcome, neonatal encephalopathy, five‐minute Apgar score < 4, neonatal resuscitation, admission to neonatal intensive care unit for 96 h or more. Conclusion We were unable to provide robust evidence of the effectiveness of FBSLM to improve the specificity of the CTG in the assessment of fetal wellbeing.