Study	Reason for exclusion
Bastide 1990	Unpublished data from 1990 available only. Intervention was whirlpool bath and was inadequate to confirm immersion of the pregnant abdomen was possible. We contacted the author for further information, but nothing was provided.
Benfield 2001	The intervention was not consistent with immersion of the pregnancy abdomen, as women were in a limited depth of water; were asked to adopt semi‐recumbent positions on a partially inflated air raft with attached head pillow (authors description) for 1 hour, and had cannulation to facilitate repeat blood samples. All of which limits mobility and is not consistent with water immersion in labour.
Cai 2005	Cases drawn from existing records, not randomised design.
Calvert 2000	The intervention was inappropriate as the study was to compare the effect of the essential oil of ginger compared to essential oil of lemon grass rather than water immersion.
Cluett 2001	Women had all been diagnosed as having dystocia in the first stage of labour (less than 1 cm/hr progress after established labour), and therefore at increased risk of complications and this does not meet participant inclusion criteria.
Cluett 2004	Women had all been diagnosed as having dystocia in the first stage of labour (less than 1 cm/hr progress after established labour), and therefore at increased risk of complications and this does not meet participant inclusion criteria.
Henrique 2015	The intervention is hot water spray, or shower, and not immersion in water and hence is not the intervention of this review.
Irion 2011	Antenatal women standing in water versus antenatal women sat in water with legs elevated and peripheral oedema assessed. Not immersion and not labour or birth.
Kashanian 2013	The participants are antenatal women, not in labour or during birth.
Khadijeh 2015	The intervention is warm water shower, and not immersion in water and hence is not the intervention of this review as the physiological impact of a shower is considered to be different to immersion.
Labrecque 1999	The Intervention does not meet the inclusion criteria for this review, as 3 interventions were compared (1) ISWs, (2) transcutaneous electrical nerve stimulation and (3) standard care that included back massage, and all has access to a whirlpool bath and liberal mobilisation, and therefore is not specifically about water immersion.
Lee 2013	The intervention is inappropriate being a 20‐minute shower, not immersion in water during first stage of labour.
Malarewicz 2005	Inadequate description of the pool to confirm immersion. The only outcome provided is cervical dilation between 2 time points, which is a subjective measurement by the caregiver, of a non linear outcome. No data were provided on length of labour, which is outcome used within this review. No other outcome was provided, despite direct request for non published data to authors.
Zou 2008	The design description indicated this as a cohort study not a randomised trial.

ISW: intracutaneous sterile water injection