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. 2018 May 16;2018(5):CD000111. doi: 10.1002/14651858.CD000111.pub4

Schorn 1993.

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 could not 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.
 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:

  1. gestation between 36‐41 weeks;

  2. no major obstetric or medical complication;

  3. active labour between 4‐7 cm cervical dilatation;

  4. intact membranes on entry;

  5. normal FHR patterns;

  6. ambulation and analgesics were allowed.
Interventions Immersion in water during first stage of labour.
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 outcomes:

  1. Maternal age;

  2. gestational age;

  3. ethnicity;

  4. parity;

  5. water temperature;

  6. duration in bath;

  7. *use of analgesia;

  8. *augmentation;

  9. cervical dilatation;

  10. *duration of first stage of labour;

  11. *duration of second stage of labour;

  12. duration of admission to delivery;

  13. duration of ruptured membranes;

  14. blood pressure;

  15. pulse;

  16. maternal temperature;

  17. *method of delivery;


Fetal outcomes:

  1. *FHR patterns;

  2. Apgar score at 1 minute;

  3. *Apgar score at 5 minutes;

  4. neonatal weight;.


Additional outcomes:

  1. *postnatal maternal infections;

  2. re‐admissions to hospital.
Notes Academic hospital, Houston, Texas, USA. December 1990 to December 1991
Funding: not reported
Declaration of interest: not reported
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 of participants and personnel (performance bias) 
 All outcomes High risk High risk of bias could have been introduced because women, carers and researcher could not be blind to group allocation after randomisation due to the nature of the intervention
Blinding of outcome assessment (detection bias) 
 All outcomes Unclear risk No information provided
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