Methods	Randomisation by sealed opaque, sequentially numbered envelopes containing the code. Methodological qualities: selection bias: none; performance bias: high risk of bias could have been introduced because researcher cannot be blind to group allocation after randomisation; exclusion bias: low risk of bias as only 8/200 did not enter bath. Analysed according to intention to treat; bias conclusion: moderate bias. 1 or more criteria partially met. May raise some doubt about the results
Participants	Group 1: n = 100: the “early bath group”. Group 2: n = 100: the “late bath group”. Regional referral hospital in the west of Sweden. Inclusion criteria: gestation > 34 weeks; low risk; singleton; cephalic presentation; spontaneous labour; contractions 3/10 minutes and/or ruptured membranes with cervical dilatation less than 3 cm. Normal FHR pattern. Ambulation and analgesics were allowed.
Interventions	All women used an oval tub that was 1.5 m long and 40 cm deep. It contained 300 L of waters at a temperature not more than 38 degrees Celsius. Group 1: the “early bath group” had a cervical dilatation of less than 5 cm when immersed in water. Group 2: the “late bath group” had a cervical dilation of 5 cm or more when immersed in water No mention of 1-to-1 care or not.
Outcomes	Maternal outcomes: *use of analgesia/anaesthesia; *augmentation of labour; duration of labour and birth; *mode of delivery; *maternal infection; *abnormal FHR patterns needing intervention; *neonatal condition; *admittance to NICU or high dependency care unit; *neonatal infection rates (studies that describe additional outcomes that may be of importance will be mentioned in the text); parity; maternal age; birthweight; Bishop score before randomisation.
Notes	Duration of labour not in acceptable format. Early group 9.80 hours and late group 8. 48 hours P < 0.004. Primipara: 72/100 in early group and 60/100 in late group. Maternal mean age: 26.3 early group; 27.2 late group. Mean birthweight: 3550 g early group; 3616 g late group. Performance bias: caregivers were not blind to group allocation. Not recorded if results were analysed blind. Exclusion bias: *women did not enter bath - groups not mentioned. Thus moderate rate of bias may be present.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated.
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes containing allocation.
Blinding (performance bias and detection bias) All outcomes	High risk	High risk of bias could have been introduced because women, carers and researcher cannot be blind to group allocation after randomisation due to the nature of the intervention
Incomplete outcome data (attrition bias) All outcomes	Low risk	1 woman in early bath group did not use water, compared to 7 in late bath group; however, this might be expected as a result of different degrees of progression in labour
Selective reporting (reporting bias)	Low risk	All outcomes identified in methods are reported.
Other bias	Unclear risk	Percentage of primigravida higher in early group, but likely to be due to chance No mention of 1-to-1 care or not.