Klauser 2005.

Methods	Single‐centre RCT.
Participants	360 women in labour. Control group: 1 post randomisation exclusion as no consent. Intervention group: 30 post randomisation exclusions where FPO sensor not placed and 2 additional exclusions due to randomisation issues. Inclusion criteria: nonreassuring CTG, ≧ 28 weeks' gestation, single fetus, cephalic presentation, cervical dilatation of at least 2 cm and at station ‐5 or below, ruptured amniotic membranes (spontaneous or artificial). Exclusion criteria: planned caesarean section, contraindication to vaginal birth (including genital herpes, transverse lie), unexplained vaginal bleeding, placenta praevia, ominous CTG requiring immediate birth, known HIV infection, hepatitis B or C, unable to give consent due to intrapartum parenteral analgesia.
Interventions	Control group: fetal heart rate monitoring (CTG) (Doppler/fetal scalp electrode). Study group: CTG plus fetal pulse oximetry (Nellcor OxiFirst). Protocol for action with reassuring fetal oximetry (≧ ≥30%) and nonreassuring values (< 30% for 3 minutes).
Outcomes	Primary outcome: caesarean section for nonreassuring fetal status. Maternal outcomes: caesarean section for all indications; caesarean section for dystocia; amnioinfusion and length of labour. Neonatal outcomes including: Apgar scores; umbilical cord blood gases; resuscitation; admission to NICU.
Notes	Further data were requested, no response. Sample size calculation: yes, based on reduction in caesarean section rate for nonreassuring fetal status. This was revised following the interim analysis due to a higher than anticipated caesarean section rate in the control group, meaning that a 50% reduction in caesareans would require less participants than originally though. The study ceased at that time. Fetal oximetry system used: Nellcor OxiFirst.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method of randomisation not stated. No response from request to the authors for clarification.
Allocation concealment (selection bias)	Unclear risk	Unclear. No mention in the report, although two participants were excluded on the basis of "randomization issues".
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants were unblinded. It would not have been feasible to blind the clinician or participant, given that FSpO2 values were used for clinical judgement.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It is unclear if the outcome assessors were blinded to group allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No evidence of incomplete outcome data ‐ the flowchart in the published report accounts for all those enrolled. The trial was ceased following an interim analysis, at which time it was determined that a total of 300 of the original planned 400 would have adequate power to detect a 50% reduction in the primary outcome, caesarean section. Some recruitment occurred while the interim analysis was in progress, meaning that a total of 327 women were randomised. Of these, there were 32 postrandomisation exclusions in the fetal oximetry group and 1 in the control group,
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting. The flowchart in the published report accounts for all those enrolled.
Other bias	Low risk	No evidence of other bias, although there is no evidence of trial registration or study protocol publication.