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. Author manuscript; available in PMC: 2014 Apr 10.
Published in final edited form as: Cochrane Database Syst Rev. 2009 Apr 15;(2):CD000111. doi: 10.1002/14651858.CD000111.pub3
Methods Randomisation by packets containing random computer-generated codes.
Methodological qualities:

  1. selection bias: high risk - the researcher knew group allocation before obtaining informed consent;

  2. performance bias: high risk of bias could have been introduced because researcher cannot be blind to group allocation after randomisation;

  3. exclusion bias: low risk of bias - no exclusions. Main outcome not stated. Determine safety and effect of water immersion on women in labour. Most women stayed in the tub for 30-45 minutes.

  4. Bias conclusion: moderate bias. 1 or more criteria partially met. May raise some doubt about the results
Participants Study group: n = 45.
Control group: n = 48.
Inclusion criteria:
gestation between 36-41 weeks;
no major obstetric or medical complication;
active labour between 4-7 cm cervical dilatation;
intact membranes on entry;
normal FHR patterns;
ambulation and analgesics were allowed.
Interventions Study group: The use of a hot tub with air jets and with a moulded seat during labour.
Bath temperature between 32-41 degrees Celsius.
Control group: no water immersion during labour. Showers were allowed
First stage of labour.
Outcomes Maternal age;
gestational age;
ethnicity;
parity;
water temperature;
duration in bath;
*use of analgesia;
*augmentation;
cervical dilatation;
*duration of first stage of labour;
*duration of second stage of labour;
duration of admission to delivery;
duration of ruptured membranes;
blood pressure;
pulse;
maternal temperature;
*method of delivery;
*FHR patterns;
Apgar score at 1 minute;
*Apgar score at 5 minutes;
neonatal weight;
*postnatal maternal infections;
re-admissions to hospital.
Notes Academic hospital, Houston, Texas, USA. December 1990 to December 1991
Risk of bias
Bias Authors’ judgement Support for judgement
Random sequence generation (selection bias) Low risk Computer-generated code.
Allocation concealment (selection bias) High risk Midwife know the allocation at the time of recruitment, and risk of bias acknowledged but women apparently would not be recruited if they did not know which allocation they had
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 All participants are accounted for throughout study with no withdrawals
Selective reporting (reporting bias) Low risk All outcomes mentioned in method are reported, and seem appropriate for the study and topic
Other bias Unclear risk There were significantly more primigravid women in water group, which could affect outcomes, and is a confounding variable