Methods	Randomisation was computer generated, and then recorded on a list (paper copy), where the next allocation was concealed from the research until the next woman had provided consent, was recruited and thus being allocated. Methodological qualities: selection bias: none apparent; 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 4 of 58 in water group did not get water as required CS prior to immersion, and 2 of 56 in control group also required CS prior to reaching cervical dilation of 6cm. Analysed according to intention to treat; bias conclusion: high risk of bias, where 1 or more criteria are not met may cause plausible bias that seriously weakens confidence in the results
Participants	Power calculation undertaken. Water n = 58. Control n = 56. Full term, nulliparous, live, cephalic presentation, no complications, cervical dilation of 6 cm or less in established labour
Interventions	Control group received standard care, including cardiotocography on admission, ambulation, amniotomy and oxytocin augmentation if now cervical progress over 3 hours, intermittent auscultation during labour Intervention group as above with immersion in water when cervix had reached 6-7 cm dilated, for 60 minutes First stage of labour study, all women received 1-to-1 care from the researcher Pool was 194 litres, equipped with a heater. Water temperature ranged from 27 to 38 degrees Celsius
Outcomes	Pain score on 5-point behavioural scale and numerical pain score from 0 to 10, at 6-7 cm dilated and again 1 hour later In addition the following data were collected: use of augmentation, amniotic liquor conditions, duration of labour, perineal condition, gestational age, Apgar score at 1 and 5 minutes, maternal and water temperature
Notes	Study done in Sao Paulo, Brazil.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated random list.
Allocation concealment (selection bias)	High risk	Each allocation on the list was covered with a tab, which was removed by the researcher after consent form signed by next participant. This description suggests the process could be open to tampering
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	Flow chart detailed participants from eligibility to completion; no attrition after instigation of allocated care
Selective reporting (reporting bias)	Low risk	All the data mentioned in the methods, and that would reasonably be expected of this study are reported
Other bias	Unclear risk	All women had 1-to-1 care,which is known to affect outcomes, but is common for water immersion care. In this study the care was from the researcher, regardless of group