Table 4.
Results of subgroup analysis of interventions on outcomes of water immersion for labour and waterbirth compared with standard care
| Outcome | Studies | Sample | Effect OR (95% CI) model |
Heterogeneity Q (p) I2% |
| Labour Induction* | ||||
| Obstetric units | 2 | 604 Immersion 792 Standard care |
0.32 (0.06 to 1.58) Random effects |
18 (<0.01) 94 |
| Amniotomy* | ||||
| Obstetric units | 4 | 306 Immersion 709 Standard care |
0.95 (0.62 to 1.46) Random effects |
5 (0.17) 40 |
| 2010 and earlier | 3 | 192 Immersion 250 Standard care |
0.87 (0.46 to 1.64) Random effects |
4 (0.13) 51 |
| 2011 and later | 2 | 420 Immersion 765 Standard care |
0.56 (0.15 to 2.02) Random effects |
14 (<0.01) 93 |
| Augmentation* | ||||
| Obstetric units | 2 | 203 Immersion 605 Standard care |
0.48 (0.16 to 1.51) Random effects |
6 (0.02) 83 |
| 2011 and later | 2 | 420 Immersion 765 Standard care |
0.32 (0.05 to 2.24) Random effects |
19 (<0.01) 95 |
| Opioid use | ||||
| 2010 and earlier | 6 | 4298 Immersion 6565 Standard care |
0.23 (0.08 to 0.70) Random effects |
95 (<0.01) 95 |
| 2011 and later | 2 | 1641 Immersion 14 887 Standard care |
0.17 (0.15 to 0.20) Fixed effects |
0 (0.54) 0 |
| Epidural* | ||||
| Obstetric units | 6 | 4104 Immersion 6889 Standard care |
0.26 (0.08 to 0.83) Random effects |
89 (<0.01) 94 |
| 2010 and earlier | 6 | 4104 Immersion 6889 Standard care |
0.26 (0.08 to 0.83) Random effects |
89 (<0.01) 94 |
| Pain | ||||
| 2010 and earlier | 3 | 182 Immersion 188 Standard care |
0.53 (0.27 to 1.03) Random effects |
6 (0.05) 68 |
| 2011 and later | 5 | 417 Immersion 413 Standard care |
0.15 (0.06 to 0.42) Random effects |
48 (<0.01) 92 |
| Caesarean delivery | ||||
| 2010 and earlier | 4 | 790 Immersion 745 Standard care |
1.05 (0.63 to 1.74) Fixed effects |
3 (0.43) 0 |
| 2011 and later | 4 | 400 Immersion 830 Standard care |
0.84 (0.32 to 2.23) Fixed effects |
6 (0.12) 48 |
| Shoulder dystocia | ||||
| Obstetric units | 6 | 5528 Immersion 21 155 Standard care |
1.06 (0.64 to 1.74) Fixed effects |
4 (0.60) 0 |
| 2010 and earlier | 3 | 4007 Immersion 6335 Standard care |
0.88 (0.42 to 1.83) Fixed effects |
2 (0.39) 0 |
| 2011 and later | 4 | 11 773 Immersion 31 252 Standard care |
0.87 (0.33 to 2.26) Random effects |
11 (0.01) 73 |
| Intact perineum | ||||
| Obstetric units | 14 | 6170 Immersion 8866 Standard care |
1.55 (1.12 to 2.16) Random effects |
147 (<0.01) 91 |
| Midwifery-led units | 3 | 17 079 Immersion 23 249 Standard care |
1.07 (0.91 to 1.26) Random effects |
15 (<0.01) 87 |
| Nulliparas | 5 | 1065 Immersion 894 Standard care |
1.59 (1.01 to 2.50) Random effects |
12 (0.01) 68 |
| Waterbirth versus no water | 8 | 954 Immersion 1696 Standard care |
1.35 (0.67 to 2.72) Random effects |
83 (<0.01) 92 |
| 2010 and earlier | 7 | 4958 Immersion 6949 Standard care |
1.28 (0.90 to 1.82) Random effects |
39 (<0.01) 85 |
| 2011 and later | 10 | 18 292 Immersion 28 871 Standard care |
1.59 (1.22 to 2.07) Random effects |
156 (<0.01) 94 |
| OASI | ||||
| Obstetric units | 13 | 10 720 Immersion 57 870 Standard care |
0.85 (0.57 to 1.30) Random effects |
51 (<0.001) 77 |
| Midwifery-led units | 2 | 6827 Immersion 10 558 Standard care |
0.71 (0.47 to 1.08) Fixed effects |
0 (0.527) 0 |
| Nulliparas | 2 | 870 Immersion 540 Standard care |
1.25 (0.42 to 3.71) Fixed effects |
1 (0.385) 0 |
| Waterbirth versus no water | 3 | 408 Immersion 550 Standard care |
0.57 (0.19 to 1.69) Fixed effects |
1 (0.681) 0 |
| 2010 and earlier | 6 | 5493 Immersion 7517 Standard care |
0.73 (0.58 to 0.91) Fixed effects |
8 (0.16) 37 |
| 2011 and later | 9 | 13 298 Immersion 67 382 Standard care |
0.78 (0.48 to 1.28) Random effects |
42 (<0.01) 81 |
| Episiotomy* | ||||
| Obstetric units | 14 | 6177 Immersion 13 548 Standard care |
0.17 (0.11 to 0.28) Random effects |
109 (<0.001) 88 |
| Nulliparas | 3 | 886 Immersion 582 Standard care |
0.10 (0.02 to 0.60) Random effects |
14 (<0.001) 86 |
| Waterbirth versus no water | 5 | 691 Immersion 1022 Standard care |
0.63 (0.02 to 0.20) Random effects |
14 (0.008) 71% |
| 2010 and earlier | 7 | 4927 Immersion 6912 Standard care |
0.21 (0.11 to 0.41) Random effects |
52 (<0.01) 88 |
| 2011 and later | 8 | 7831 Immersion 16 888 Standard care |
0.09 (0.03 to 0.25) Random effects |
53 (<0.01) 87 |
| Postpartum faemorrhage | ||||
| Obstetric units | 13 | 7040 Immersion 29 555 Standard care |
0.75 (0.60 to 0.94) Random effects |
30 (0.002) 60 |
| Midwifery-led units | 2 | 10 558 Immersion 16 738 Standard care |
0.39 (0.08 to 1.86) Random effects |
56 (<0.001) 98 |
| Waterbirth versus no mater | 5 | 758 Immersion 1177 Standard care |
1.02 (0.76 to 1.36) Fixed effects |
4 (0.439 0 |
| 2010 and earlier | 3 | 4007 Immersion 6348 Standard care |
0.72 (0.59 to 0.88) Random effects |
2 (0.30) 17 |
| 2011 and later | 12 | 13 591 Immersion 39 945 Standard care |
0.76 (0.48 to 1.20) Random effects |
97 (<0.01) 89 |
| Manual removal of placenta | ||||
| Obstetric units | 4 | 1239 Immersion 1654 Standard care |
0.78 (0.37 to 1.64) Fixed effects |
6 (0.105) 51 |
| 2010 and earlier | 2 | 701 Immersion 771 Standard care |
0.48 (0.21 to 1.11) Fixed effects |
0 (0.91) 0 |
| 2011 and later | 3 | 538 Immersion 883 Standard care |
1.48 (0.50 to 4.38) Fixed effects |
4 (0.16) 45 |
| Maternal satisfaction | ||||
| Obstetric units | 5 | 1802 Immersion 1568 Standard care |
2.02 (1.28 to 3.19) Random effects |
24 (<0.01) 83 |
| 2010 and earlier | 4 | 1815 Immersion 1519 Standard care |
1.64 (0.83 to 3.24) Random effects |
22 (<0.01) 86 |
| 2011 and later | 2 | 372 Immersion 438 Standard care |
2.55 (1.54 to 4.23) Random effects |
2 (0.16) 50 |
| APGAR | ||||
| Obstetric units | 18 | 10 286 Immersion 54 361 Standard care |
0.85 (0.66 to 1.08) Random effects |
29 (0.047) 38 |
| Midwifery-led units | 3 | 17 092 Immersion 18,31 Standard care |
0.33 (0.07 to 1.54) Random effects |
57 (<0.001) 96 |
| Waterbirth versus no water | 6 | 614 Immersion 655 Standard care |
1.07 (0.76 to 1.51) Fixed effects |
3 (0.643) 0 |
| 2010 and earlier | 8 | 4184 Immersion 6476 Standard care |
1.00 (0.77 to 1.29) Fixed effects |
7 (0.120) 39 |
| 2011 and later | 12 | 21 931 Immersion 65 781 Standard care |
0.52 (0.25 to 1.05) Random effects |
101 (<0.001) 89 |
| Neonatal death | ||||
| Midwifery-led units | 2 | 16 786 Immersion 26 722 Standard care |
0.91 (0.61 to 1.34) Fixed effects |
1 (0.297) 8 |
| Cord avulsion | ||||
| Obstetric units | 3 | 1874 Immersion 21 621 Standard care |
2.18 (0.34 to 11.97) Fixed effects |
1 (0.757) 0 |
| Midwifery-led units | 2 | 10 649 Immersion 16 829 Standard care |
1.92 (1.28 to 2.89) Fixed effects |
1 (0.386) 0 |
*Random effects models were used for intervention (labour induction, amniotomy, augmentation, epidural, and episiotomy) models because variation in use of these procedures is dependent on practice habits of the provider which are not otherwise controlled.
OASI, obstetric anal sphincter injury.