Comparison 1. Immersion in water versus no immersion during first stage of labour.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mode of birth (spontaneous vaginal birth)	6	2559	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.97, 1.04]
2 Mode of birth (instrumental vaginal births)	6	2559	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.70, 1.05]
3 Mode of birth (caesarean section)	7	2652	Risk Ratio (M‐H, Fixed, 95% CI)	1.27 [0.91, 1.79]
4 Use of analgesia (regional)	5	2439	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.83, 0.99]
5 Perineal trauma (third‐ or fourth‐degree tears)	4	2341	Risk Ratio (M‐H, Fixed, 95% CI)	1.36 [0.85, 2.18]
6 Admission to neonatal intensive care unit	2	1511	Risk Ratio (M‐H, Random, 95% CI)	1.30 [0.42, 3.97]
7 Neonatal infection	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	2.00 [0.50, 7.94]
8 Neonate temperature	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
8.1 Temperature greater than 37.8 degrees C as an indicator for infection	1	274	Risk Ratio (M‐H, Fixed, 95% CI)	1.0 [0.06, 15.83]
9 Estimated blood loss (mL)	2	153	Mean Difference (IV, Fixed, 95% CI)	‐14.33 [‐63.03, 34.37]
10 Postpartum haemorrhage	1	274	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [0.80, 3.13]
11 Use of analgesia (pharmacological ‐ pethidine/narcotic)	3	1180	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.59, 1.96]
12 Use of any analgesia	3	487	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.88, 1.12]
13 Use of analgesia (pharmacological ‐ any)	2	394	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.80, 1.39]
14 Maternal infection during labour/postnatal period (perineal, systemic, uterine or increase in temperature)	5	1295	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.50, 1.96]
15 Artificial rupture of membranes	3	926	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.90, 1.16]
16 Use of oxytocin for augmentation of labour	4	1019	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.72, 1.15]
17 Use of non‐pharmacological analgesia (transcutaneous nerve stimulation (TENS)	1	785	Risk Ratio (M‐H, Fixed, 95% CI)	1.25 [0.34, 4.61]
18 Duration of first stage (minutes)	5	1295	Mean Difference (IV, Fixed, 95% CI)	‐11.53 [‐45.42, 22.36]
19 Duration of second stage (minutes)	6	1403	Mean Difference (IV, Random, 95% CI)	1.12 [‐5.23, 7.48]
20 Duration of third stage (minutes)	2	1059	Mean Difference (IV, Fixed, 95% CI)	0.25 [‐1.10, 1.60]
21 Duration of total labour (all three stages minutes)	1	120	Mean Difference (IV, Fixed, 95% CI)	‐27.5 [‐133.05, 78.05]
22 Perineal trauma (intact)	4	1277	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [1.01, 1.37]
23 Perineal trauma (second‐degree tears)	4	1212	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.74, 1.20]
24 Perineal trauma (episiotomy)	4	1212	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.80, 1.09]
25 Self reports pain score on visual analogue scale of 0‐10	2		Mean Difference (IV, Random, 95% CI)	Subtotals only
25.1 Pain score at start of assessment period (time zero)	2	141	Mean Difference (IV, Random, 95% CI)	0.15 [‐0.79, 1.08]
25.2 Pain score up to 60 minutes later	2	141	Mean Difference (IV, Random, 95% CI)	‐0.81 [‐1.34, ‐0.28]
26 Pain intensity (experience of moderate to severe pain)	1		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
26.1 Ordinal description as moderate to severe, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.62, 0.91]
26.2 VAS scale 8 to 10, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.58, 0.90]
26.3 Ordinal scale pain faces 4 to 5, 30 mins after randomisation	1	120	Risk Ratio (M‐H, Fixed, 95% CI)	0.67 [0.51, 0.90]
26.4 Ordinal description as moderate to severe, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.63, 0.91]
26.5 VAS scale 8 to 10, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	1.21 [0.69, 2.11]
26.6 Ordinal scale pain faces 4 to 5, 1 hr after randomisation	1	117	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.53, 0.86]
26.7 Ordinal description as moderate to severe, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.76 [0.59, 0.98]
26.8 VAS scale 8 to 10, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.66, 1.05]
26.9 Ordinal scale pain faces 4 to 5, 2 hrs after randomisation	1	57	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.52, 0.98]
26.10 Ordinal description as moderate to severe, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.52 [0.23, 1.16]
26.11 VAS scale 8 to 10, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.39, 1.23]
26.12 Ordinal scale pain faces 4 to 5, 3 hrs after randomisation	1	32	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.25, 1.27]
26.13 Ordinal description as moderate to severe, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.64 [0.50, 0.82]
26.14 VAS scale 8 to 10, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.62 [0.49, 0.80]
26.15 Ordinal scale pain faces 4 to 5, 24 hrs after randomisation	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.54, 0.87]
27 Systolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐7.20 [‐13.12, ‐1.28]
28 Diastolic blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.20 [‐13.70, ‐6.70]
29 Mean arterial blood pressure	1	120	Mean Difference (IV, Fixed, 95% CI)	‐10.5 [‐14.68, ‐6.32]
30 Preference for care in subsequent labour (Does not wish to use bath with next labour/birth)	1	119	Risk Ratio (M‐H, Fixed, 95% CI)	0.38 [0.14, 0.98]
31 Postpartum depression (EPDS more than 11)	2	370	Risk Ratio (M‐H, Fixed, 95% CI)	1.38 [0.85, 2.24]
32 Abnormal fetal heart rate patterns	3	487	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.34, 1.67]
33 Presence of meconium‐stained liquor	4	1200	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.64, 1.33]
34 Apgar score less than seven at five minutes	5	1834	Risk Ratio (M‐H, Fixed, 95% CI)	1.58 [0.63, 3.93]
35 Apgar score at five minutes	2	893	Mean Difference (IV, Fixed, 95% CI)	‐0.03 [‐0.11, 0.06]
36 Umbilical artery pH less than 7.20	1	110	Risk Ratio (M‐H, Fixed, 95% CI)	5.18 [0.25, 105.51]
37 Breastfeeding ‐ not breastfeeding after six weeks post birth	2	363	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [0.64, 2.15]