Woolnough 2009.

Methods	Single‐centre study from UK
Participants	75 female patients undergoing elective caesarean section for a singleton pregnancy greater than 37 weeks of gestation under combined spinal‐epidural anaesthesia Exclusion criteria: pyrexia, pre‐eclampsia, drug therapy other than antacids or vitamins, patients at increased risk of intraoperative bleeding
Interventions	Group 1 (n = 25) room temperature intravenous fluids: 2.0 ± 0.4 litres infused Group 2 (n = 25) prewarmed intravenous fluids: 2.1 ± 0.4 litres infused Group 3 (n = 23) in‐line warming: 2.4 ± 1.4 litres infused
Outcomes	Tympanic temperature measured every 15 minutes; blood loss; shivering; subjective feelings of hot or cold Shivering assessed using a 3‐point scale: 0 = no shivering; 1 = mild, intermittent shivering; 2 = intense, continuous shivering
Notes	Both groups of warmed fluids combined for analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	'Computer generated random numbers and sealed envelopes'
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	To maintain blinding, all groups had fluids delivered via a hotline fluid warmer, which was switched on only for group 3. The investigator was not allowed to touch any fluid bags or to give any IV drugs
Blinding of outcome assessment (detection bias) All outcomes	Low risk	A blinded investigator recorded temperature and assessed the degree of shivering
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
Selective reporting (reporting bias)	Low risk	No evidence of this
Other bias	Low risk	None