Background
Methods
Source of data and study population
Outcomes
-
Intrapartum transfer before birth
-
Intrapartum caesarean section
-
Straightforward vaginal birth, defined as birth without forceps, ventouse or caesarean, with no 3rd or 4th degree tear and no blood transfusion.
-
Transfer for failure to progress in the first stage of labour
-
Transfer before birth for ‘potentially urgent reasons’
-
Transfer for pain relief or epidural analgesia
-
Augmentation in labour with oxytocin
-
Epidural or spinal analgesia
Statistical analysis
Ethical approval
Results
Home | FMU | AMU | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
n = 4013 | n = 4831 | n = 7733 | ||||||||||
No immersion | Immersion | No immersion | Immersion | No immersion | Immersion | |||||||
n = 2002 | n = 2011 | n = 2216 | n = 2615 | n = 4807 | n = 2926 | |||||||
n | %1
| n | %1
| n | %1
| n | %1
| n | % | n | %1
| |
Maternal age
| ||||||||||||
Mean (SD) | 29.7 | (5.3) | 30.6 | (4.7) | 26.2 | (5.6) | 27.6 | (5.7) | 26.5 | (5.6) | 27.5 | (5.6) |
Under 20 | 87 | 4.3 | 30 | 1.5 | 297 | 13.4 | 248 | 9.5 | 566 | 11.8 | 272 | 9.3 |
20–24 | 241 | 12.0 | 159 | 7.9 | 609 | 27.5 | 554 | 21.2 | 1300 | 27.0 | 626 | 21.4 |
25–29 | 607 | 30.3 | 611 | 30.4 | 659 | 29.7 | 783 | 29.9 | 1465 | 30.5 | 901 | 30.8 |
30–34 | 675 | 33.7 | 808 | 40.2 | 474 | 21.4 | 735 | 28.1 | 1048 | 21.8 | 795 | 27.2 |
35–39 | 350 | 17.5 | 362 | 18.0 | 161 | 7.3 | 261 | 10.0 | 391 | 8.1 | 303 | 10.4 |
40+ | 39 | 1.9 | 37 | 1.8 | 12 | 0.5 | 32 | 1.2 | 29 | 0.6 | 22 | 0.8 |
Missing | 3 | 0.1 | 4 | 0.2 | 4 | 0.2 | 2 | 0.1 | 8 | 0.2 | 7 | 0.2 |
Ethnicity
| ||||||||||||
White | 1899 | 94.9 | 1898 | 94.4 | 2030 | 91.6 | 2428 | 92.8 | 3876 | 80.6 | 2548 | 87.1 |
Non-white | 102 | 5.1 | 108 | 5.4 | 186 | 8.4 | 186 | 7.1 | 919 | 19.1 | 369 | 12.6 |
Missing | 1 | 0.0 | 5 | 0.2 | 0 | 0.0 | 1 | 0.04 | 12 | 0.3 | 9 | 0.3 |
Understanding English
| ||||||||||||
Fluent | 1983 | 99.1 | 2004 | 99.7 | 2111 | 95.3 | 2563 | 98.0 | 4320 | 89.9 | 2755 | 94.2 |
Not fluent | 17 | 0.8 | 4 | 0.2 | 96 | 4.3 | 52 | 2.0 | 471 | 9.8 | 159 | 5.4 |
Missing | 2 | 0.1 | 3 | 0.1 | 9 | 0.4 | 0 | 0.0 | 16 | 0.3 | 12 | 0.4 |
Marital/Partner status
| ||||||||||||
Married/Living together | 1881 | 94.0 | 1924 | 95.7 | 1913 | 86.3 | 2380 | 91.0 | 4111 | 85.5 | 2587 | 88.4 |
Single/unsupported by partner | 110 | 5.5 | 75 | 3.7 | 276 | 12.5 | 208 | 8.0 | 638 | 13.3 | 282 | 9.6 |
Missing | 11 | 0.5 | 12 | 0.6 | 27 | 1.2 | 27 | 1.1 | 58 | 1.2 | 57 | 1.9 |
Body mass index (kg/m
2
)
| ||||||||||||
Not recorded | 391 | 19.5 | 371 | 18.4 | 334 | 15.1 | 484 | 18.5 | 810 | 16.8 | 509 | 17.4 |
Less than 18.5 | 32 | 1.6 | 42 | 2.1 | 60 | 2.7 | 51 | 2.0 | 138 | 2.9 | 87 | 3.0 |
18.5–24.9 | 1052 | 52.6 | 1077 | 53.6 | 1159 | 52.3 | 1412 | 54.0 | 2505 | 52.1 | 1615 | 55.2 |
25.0–29.9 | 406 | 20.3 | 403 | 20.0 | 502 | 22.7 | 514 | 19.7 | 1019 | 21.2 | 551 | 18.8 |
30.0–35.0 | 109 | 5.4 | 108 | 5.4 | 157 | 7.1 | 153 | 5.9 | 321 | 6.7 | 158 | 5.4 |
Missing | 12 | 0.6 | 10 | 0.5 | 4 | 0.2 | 1 | 0.0 | 14 | 0.3 | 6 | 0.2 |
Index of Multiple Deprivation (IMD) quintiles
| ||||||||||||
1st Least deprived | 412 | 20.6 | 427 | 21.2 | 400 | 18.1 | 606 | 23.2 | 693 | 14.4 | 476 | 16.3 |
2nd
| 408 | 20.4 | 432 | 21.5 | 475 | 21.4 | 630 | 24.1 | 733 | 15.2 | 524 | 17.9 |
3rd
| 454 | 22.7 | 455 | 22.6 | 464 | 20.9 | 561 | 21.5 | 921 | 19.2 | 628 | 21.5 |
4th
| 403 | 20.1 | 426 | 21.2 | 478 | 21.6 | 422 | 16.1 | 1151 | 23.9 | 690 | 23.6 |
5th Most deprived | 314 | 15.7 | 259 | 12.9 | 392 | 17.7 | 389 | 14.9 | 1294 | 26.9 | 602 | 20.6 |
Missing | 11 | 0.5 | 12 | 0.6 | 7 | 0.3 | 7 | 0.3 | 15 | 0.3 | 6 | 0.2 |
Gestation (completed weeks)
| ||||||||||||
Mean (SD) | 39.7 | (1.1) | 39.8 | (1.0) | 39.7 | (1.1) | 39.8 | (1.0) | 39.7 | (1.1) | 39.8 | (1.0) |
37 | 53 | 2.6 | 37 | 1.8 | 70 | 3.2 | 68 | 2.6 | 153 | 3.2 | 79 | 2.7 |
38 | 219 | 10.9 | 174 | 8.7 | 209 | 9.4 | 226 | 8.6 | 475 | 9.9 | 272 | 9.3 |
39 | 491 | 24.5 | 430 | 21.4 | 536 | 24.2 | 554 | 21.2 | 1179 | 24.5 | 688 | 23.5 |
40 | 739 | 36.9 | 792 | 39.4 | 833 | 37.6 | 1019 | 39.0 | 1833 | 38.1 | 1129 | 38.6 |
41 | 480 | 24.0 | 546 | 27.2 | 557 | 25.1 | 729 | 27.9 | 1134 | 23.6 | 729 | 24.9 |
42+0
| 20 | 1.0 | 32 | 1.6 | 11 | 0.5 | 19 | 0.7 | 33 | 0.7 | 29 | 1.0 |
Birth weight (grams)
| ||||||||||||
mean (SD) | 3452 | (419) | 3497 | (430) | 3391 | (419) | 3441 | (417) | 3380 | (423) | 3447 | (412) |
Less than 2500 g | 15 | 0.7 | 16 | 0.8 | 30 | 1.4 | 21 | 0.8 | 74 | 1.5 | 22 | 0.8 |
2500-2999 g | 259 | 12.9 | 217 | 10.8 | 345 | 15.6 | 325 | 12.4 | 788 | 16.4 | 351 | 12.0 |
3000-3499 g | 810 | 40.5 | 756 | 37.6 | 968 | 43.7 | 1138 | 43.5 | 2090 | 43.5 | 1247 | 42.6 |
3500-3999 g | 702 | 35.1 | 774 | 38.5 | 698 | 31.5 | 873 | 33.4 | 1465 | 30.5 | 1009 | 34.5 |
4000-4499 g | 197 | 9.8 | 210 | 10.4 | 161 | 7.3 | 229 | 8.8 | 350 | 7.3 | 267 | 9.1 |
≥4500 g | 13 | 0.6 | 33 | 1.6 | 14 | 0.6 | 29 | 1.1 | 28 | 0.6 | 20 | 0.7 |
Missing | 6 | 0.3 | 5 | 0.2 | 0 | 0.0 | 0 | 0.0 | 12 | 0.2 | 10 | 0.3 |
Events | Births | Weighted1
| Unadjusted1
| Adjusted1,2
| ||||
---|---|---|---|---|---|---|---|---|
n | n | % | (95% CI) | RR | (95% CI) | RR | (95% CI) | |
Transfer before birth
| ||||||||
Home
| ||||||||
No immersion | 661 | 1977 | 32.8 | (30.0–35.7) | 1 | - | 1 | - |
Immersion | 625 | 1999 | 30.3 | (27.9–32.9) | 0.93 | (0.83–1.03) | 0.88 | (0.79–0.99) |
FMU
| ||||||||
No immersion | 747 | 2200 | 31.5 | (27.3–36.1) | 1 | - | 1 | - |
Immersion | 590 | 2594 | 20.3 | (17.2–23.8) | 0.64 | (0.54–0.76) | 0.59 | (0.50–0.70) |
AMU
| ||||||||
No immersion | 1657 | 4749 | 34.5 | (31.3–37.8) | 1 | - | 1 | - |
Immersion | 828 | 2889 | 28.7 | (25.0–32.8) | 0.83 | (0.73–0.96) | 0.78 | (0.69–0.88) |
No pooled analysis as Wald test for interaction was p = <.001
| ||||||||
Intrapartum caesarean section
| ||||||||
Home
| ||||||||
No immersion | 150 | 2000 | 7.8 | (6.1–10.0) | 1 | - | 1 | - |
Immersion | 146 | 2010 | 7.5 | (6.2–9.1) | 0.96 | (0.73–1.27) | 0.84 | (0.63–1.11) |
FMU
| ||||||||
No immersion | 170 | 2216 | 7.1 | (5.4–9.2) | 1 | - | 1 | - |
Immersion | 133 | 2615 | 5.0 | (4.2–6.0) | 0.71 | (0.52–0.96) | 0.61 | (0.44–0.84) |
AMU
| ||||||||
No immersion | 356 | 4801 | 7.2 | (6.1–8.5) | 1 | - | 1 | - |
Immersion | 195 | 2922 | 6.9 | (5.4–8.7) | 0.95 | (0.74–1.24) | 0.87 | (0.67–1.13) |
Combined home, FMU and AMU (Wald test p = 0.179)
| ||||||||
No immersion | 676 | 9017 | 7.3 | (6.4–8.2) | 1 | - | 1 | - |
Immersion | 474 | 7547 | 6.5 | (5.6–7.5) | 0.90 | (0.75–1.08) | 0.80 | (0.67–0.97) |
Straightforward vaginal birth
3
| ||||||||
Home
| ||||||||
No immersion | 1521 | 1985 | 76.5 | (73.6–79.3) | 1 | - | 1 | - |
Immersion | 1517 | 1999 | 76.2 | (73.8–78.4) | 1.00 | (0.95–1.04) | 1.02 | (0.97–1.07) |
FMU
| ||||||||
No immersion | 1665 | 2209 | 77.2 | (73.2–80.8) | 1 | - | 1 | - |
Immersion | 2121 | 2607 | 82.3 | (79.8–84.5) | 1.07 | (1.01–1.12) | 1.09 | (1.04–1.15) |
AMU
| ||||||||
No immersion | 3421 | 4749 | 72.3 | (69.4–75.0) | 1 | - | 1 | - |
Immersion | 2145 | 2886 | 73.0 | (68.9–76.8) | 1.01 | (0.95–1.07) | 1.05 | (0.99–1.10) |
Combined home, FMU and AMU (Wald test p = 0.078)
| ||||||||
No immersion | 6607 | 8943 | 73.7 | (71.5–75.7) | 1 | - | 1 | - |
Immersion | 5783 | 7492 | 76.1 | (73.5–78.5) | 1.02 | (0.98–1.06) | 1.05 | (1.02–1.09) |
Events | Births | Weighted1
| Unadjusted1
| Adjusted1,2
| ||||
---|---|---|---|---|---|---|---|---|
n | n | % | (95% CI) | RR | (95% CI) | RR | (95% CI) | |
Transfer for failure to progress in 1st stage of labour
| ||||||||
Home
| ||||||||
No immersion | 236 | 1997 | 11.0 | (9.4–12.9) | 1 | - | 1 | - |
Immersion | 224 | 2004 | 10.9 | (9.6–12.5) | 0.99 | (0.81–1.22) | 0.94 | (0.77–1.16) |
FMU
| ||||||||
No immersion | 212 | 2203 | 8.8 | (7.1–10.8) | 1 | - | 1 | - |
Immersion | 216 | 2603 | 7.5 | (6.2–9.0) | 0.85 | (0.67–1.06) | 0.80 | (0.63–1.02) |
AMU
| ||||||||
No immersion | 410 | 4756 | 8.5 | (6.7-10.6) | 1 | - | 1 | - |
Immersion | 250 | 2900 | 8.4 | (7.0–10.1) | 0.99 | (0.77–1-27) | 0.98 | (0.78–1.23) |
Transfer for ‘potentially urgent reasons’
| ||||||||
Home
| ||||||||
No immersion | 191 | 1997 | 9.5 | (7.9–11.2) | 1 | - | 1 | - |
Immersion | 210 | 2004 | 10.4 | (9.1–11.9) | 1.10 | (0.89–1.36) | 1.06 | (0.86–1.30) |
FMU
| ||||||||
No immersion | 274 | 2203 | 11.7 | (9.9–13.8) | 1 | - | 1 | - |
Immersion | 228 | 2603 | 7.8 | (6.3–9.6) | 0.67 | (0.53–0.84) | 0.61 | (0.48–0.77) |
AMU
| ||||||||
No immersion | 587 | 4756 | 12.0 | (10.4–13.7) | 1 | - | 1 | - |
Immersion | 338 | 2900 | 11.5 | (9.6–13.8) | 0.97 | (0.79–1.19) | 0.91 | (0.75–1.09) |
Transfer for epidural or other pain relief
| ||||||||
Home
| ||||||||
No immersion | 86 | 1997 | 4.3 | (3.4–5.6) | 1 | - | 1 | - |
Immersion | 87 | 2004 | 4.1 | (3.2–5.2) | 0.94 | (0.69–1.28) | 0.88 | (0.63–1.22) |
FMU
| ||||||||
No immersion | 73 | 2203 | 3.0 | (2.0–4.6) | 1 | - | 1 | - |
Immersion | 64 | 2603 | 2.1 | (1.5–2.9) | 0.68 | (0.46–1.01) | 0.63 | (0.42–0.94) |
AMU
| ||||||||
No immersion | 297 | 4756 | 6.8 | (5.6–8.2) | 1 | - | 1 | - |
Immersion | 127 | 2900 | 5.0 | (4.0–6.3) | 0.73 | (0.59–0.92) | 0.64 | (0.51–0.78) |
Augmentation with oxytocin
| ||||||||
Home
| ||||||||
No immersion | 321 | 1991 | 15.1 | (12.9–17.5) | 1 | - | 1 | - |
Immersion | 329 | 2002 | 16.0 | (14.4–17.8) | 1.07 | (0.88–1.29) | 1.00 | (0.82–1.22) |
FMU
| ||||||||
No immersion | 371 | 2204 | 15.2 | (12.5–18.5) | 1 | - | 1 | - |
Immersion | 315 | 2602 | 10.8 | (9.3–12.5) | 0.71 | (0.58–0.87) | 0.64 | (0.52–0.79) |
AMU
| ||||||||
No immersion | 871 | 4791 | 17.7 | (15.7–19.8) | 1 | - | 1 | - |
Immersion | 453 | 2913 | 15.9 | (13.5–18.6) | 0.90 | (0.75–1.08) | 0.84 | (0.71–0.99) |
Epidural or spinal analgesia
| ||||||||
Home
| ||||||||
No immersion | 418 | 1993 | 20.5 | (18.0–23.3) | 1 | - | 1 | - |
Immersion | 440 | 2003 | 21.5 | (19.3–23.8) | 1.05 | (0.90–1.22) | 0.97 | (0.83–1.14) |
FMU
| ||||||||
No immersion | 467 | 2208 | 20.0 | (17.0–23.4) | 1 | - | 1 | - |
Immersion | 439 | 2607 | 15.9 | (13.6–18.5) | 0.80 | (0.65–0.97) | 0.72 | (0.58–0.89) |
AMU
| ||||||||
No immersion | 1149 | 4793 | 24.1 | (21.6–26.8) | 1 | - | 1 | - |
Immersion | 632 | 2915 | 22.7 | (19.5–26.3) | 0.94 | (0.81–1.10) | 0.87 | (0.75–1.00) |
Reasons for decision to transfer | Home n = 4013 | FMU n = 4831 | AMU n = 7733 | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
No immersion | Immersion | No immersion | Immersion | No immersion | Immersion | |||||||
n = 2002 | n = 2011 | n = 2216 | n = 2615 | n = 4807 | n = 2926 | |||||||
n | %1
| n | %1
| n | %1
| n | %1
| n | %1
| n | %1
| |
Not transferred | 1158 | 58.7 | 1159 | 58.7 | 1339 | 62.6 | 1826 | 71.5 | 2847 | 59.3 | 1897 | 64.7 |
‘Antepartum reasons’*
| ||||||||||||
Malposition | 3 | 0.1 | 2 | 0.1 | 4 | 0.1 | 4 | 0.1 | 15 | 0.2 | 7 | 0.2 |
Malpresentation | 13 | 0.6 | 6 | 0.3 | 13 | 0.5 | 2 | 0.1 | 24 | 0.4 | 5 | 0.2 |
Failure to progress (1st stage) | 236 | 11.0 | 224 | 10.9 | 212 | 8.8 | 216 | 7.4 | 410 | 8.3 | 250 | 8.3 |
Fetal distress (1st stage) | 45 | 2.4 | 28 | 1.4 | 97 | 4.5 | 38 | 1.5 | 154 | 3.1 | 47 | 1.8 |
Meconium staining | 102 | 5.3 | 71 | 3.2 | 133 | 5.5 | 72 | 2.6 | 236 | 4.8 | 88 | 2.8 |
Epidural request | 64 | 3.1 | 61 | 2.9 | 69 | 2.9 | 64 | 2.1 | 296 | 6.7 | 124 | 4.8 |
Hypertension | 8 | 0.4 | 7 | 0.3 | 18 | 1.0 | 4 | 0.1 | 32 | 0.6 | 5 | 0.4 |
Pain relief | 22 | 1.2 | 26 | 1.2 | 4 | 0.1 | 0 | - | 1 | <0.1 | 3 | 0.1 |
Antepartum haemorrhage | 15 | 0.7 | 7 | 0.4 | 20 | 0.9 | 5 | 0.2 | 39 | 0.8 | 11 | 0.4 |
Failure to progress (2nd stage) | 113 | 5.5 | 158 | 7.8 | 137 | 5.3 | 167 | 5.5 | 322 | 6.5 | 235 | 7.7 |
Fetal distress (2nd stage) | 15 | 0.7 | 13 | 0.6 | 12 | 0.6 | 15 | 0.5 | 62 | 1.2 | 41 | 1.4 |
Other maternal | 22 | 1.1 | 22 | 1.0 | 13 | 0.6 | 5 | 0.2 | 49 | 1.0 | 13 | 0.4 |
Other fetal | 7 | 0.4 | 6 | 0.3 | 8 | 0.4 | 5 | 0.2 | 14 | 0.3 | 5 | 0.2 |
Other | 11 | 0.5 | 5 | 0.3 | 9 | 0.3 | 2 | 0.1 | 15 | 0.2 | 8 | 0.3 |
Reason not recorded | 2 | 0.1 | 3 | 0.2 | 10 | 0.5 | 4 | 0.1 | 29 | 0.9 | 11 | 0.3 |
Postpartum transfers
| ||||||||||||
Postpartum haemorrhage | 26 | 1.3 | 24 | 1.2 | 10 | 0.5 | 25 | 1.0 | 29 | 0.9 | 22 | 0.8 |
Retained placenta | 29 | 1.4 | 47 | 2.3 | 36 | 1.8 | 41 | 1.6 | 53 | 1.0 | 37 | 1.1 |
Repair of perineal trauma | 86 | 4.2 | 113 | 5.4 | 55 | 2.4 | 84 | 3.4 | 156 | 3.1 | 97 | 3.5 |
Other maternal | 5 | 0.2 | 5 | 0.2 | 2 | 0.1 | 8 | 0.2 | 1 | <0.1 | 4 | 0.1 |
Neonatal concerns | 16 | 0.8 | 20 | 0.9 | 11 | 0.5 | 20 | 0.8 | 1 | <0.1 | 1 | 0.1 |
Other | 1 | <0.1 | 3 | 0.2 | 1 | <0.1 | 1 | <0.1 | 10 | 0.2 | 4 | 0.2 |
Transferred (timing & reason not known) | 3 | 0.2 | 1 | 0.1 | 3 | 0.1 | 7 | 0.9 | 12 | 0.4 | 11 | 0.4 |