Table 2. Labour characteristics of the study population (n = 1.457.576) and the association between these characteristcs and postpartum haemorrhage.
| Pre-eclampsia | Postpartum haemorrhage | Unadjusted odds ratio for | |||||||||||
| Yes* | No* | Yes* | No* | Total* | postpartum haemorrhage | ||||||||
| Characteristic | n | (%) | N | (%) | n | (%) | n | (%) | n | (%) | OR | (95% CI) | |
| Pregnant women | 31560 | (2.2) | 1426016 | (97.8) | 62864 | (4.3) | 1394712 | (95.7) | 1457576 | (100.0) | |||
| Presentation† | |||||||||||||
| Vertex | 28405 | (90.1) | 1346629 | (94.5) | 59701 | (95.0) | 1315333 | (94.3) | 1375034 | (94.4) | 1.00 | reference | |
| Breech | 2742 | (8.7) | 69527 | (4.9) | 2496 | (4.0) | 69773 | (5.0) | 72269 | (5.0) | 0.80 | (0.77 to 0.83) | |
| Other | 382 | (1.2) | 9327 | (0.7) | 618 | (1.0) | 9091 | (0.7) | 9709 | (0.7) | 1.54 | (1.42 to 1.66) | |
| Missing | 31 | 533 | 49 | 515 | 564 | ||||||||
| Onset of labour† | |||||||||||||
| Non-induced labour | 6700 | (21.3) | 1146966 | (80.5) | 46120 | (73.6) | 1107546 | (79.5) | 1153666 | (79.2) | 1.00 | reference | |
| Induced labour | 17438 | (55.4) | 193983 | (13.6) | 12945 | (20.6) | 198476 | (14.2) | 211421 | (14.5) | 1.52 | (1.49 to 1.55) | |
| Elective caesarean | 7334 | (23.3) | 83639 | (5.9) | 3624 | (5.8) | 87349 | (6.3) | 90973 | (6.2) | 1.02 | (0.99 to 1.06) | |
| Missing | 88 | 1428 | 175 | 1341 | 1516 | ||||||||
| Ruptured membranes, hours† | |||||||||||||
| <12 | 25617 | (86.1) | 1134348 | (82.9) | 47867 | (78.5) | 1112098 | (83.2) | 1159965 | (83.0) | 1.00 | reference | |
| ≥12 | 4132 | (13.9) | 233257 | (17.1) | 13117 | (21.5) | 224272 | (16.8) | 237389 | (17.0) | 1.35 | (1.32 to 1.37) | |
| Missing | 1811 | 58411 | 1880 | 58342 | 60222 | ||||||||
| Augmentation of labour† | |||||||||||||
| No | 22931 | (72.7) | 1141004 | (80.0) | 45180 | (71.9) | 1118755 | (80.2) | 1163935 | (79.9) | 1.00 | reference | |
| Yes | 8629 | (27.3) | 285012 | (20.0) | 17684 | (28.1) | 275957 | (19.8) | 293641 | (20.1) | 1.52 | (1.50 to 1.55) | |
| Expulsive phase, minutes† | |||||||||||||
| <60 | 27553 | (88.0) | 1186426 | (84.0) | 48349 | (77.8) | 1165630 | (84.4) | 1213979 | (84.1) | 1.00 | reference | |
| ≥60 | 3767 | (12.0) | 225148 | (16.0) | 13780 | (22.2) | 215135 | (15.6) | 228915 | (15.9) | 1.52 | (1.49 to 1.55) | |
| Missing | 240 | 14442 | 735 | 13947 | 14682 | ||||||||
| Mode of delivery† | |||||||||||||
| Spontaneous delivery | 14784 | (46.9) | 1088924 | (76.4) | 46376 | (74.0) | 1057332 | (75.9) | 1103708 | (75.8) | 1.00 | reference | |
| Assisted delivery | 3959 | (12.6) | 144854 | (10.2) | 9383 | (15.0) | 139430 | (10.0) | 148813 | (10.2) | 1.49 | (1.46 to 1.52) | |
| Elective caesarean | 7334 | (23.3) | 83639 | (5.9) | 3624 | (5.8) | 87349 | (6.3) | 90973 | (6.2) | 0.98 | (0.95 to 1.08) | |
| Emergency caesarean | 5453 | (17.3) | 107304 | (7.5) | 3275 | (5.2) | 109482 | (7.9) | 112757 | (7.7) | 0.72 | (0.70 to 0.74) | |
| Missing | 30 | 1295 | 206 | 1119 | 1325 | ||||||||
| Genital tract injury† | |||||||||||||
| Episiotomy (no)/perineal tear (no) | 23376 | (74.1) | 1024303 | (71.9) | 37681 | (60.0) | 1009998 | (72.4) | 1047679 | (71.9) | 1.00 | reference | |
| Episiotomy (no)/perineal tear (yes) | 364 | (1.2) | 23953 | (1.7) | 1679 | (2.7) | 22638 | (1.6) | 24317 | (1.7) | 1.92 | (1.83 to 2.01) | |
| Episiotomy (yes)/perineal tear (no) | 7714 | (24.5) | 371807 | (26.1) | 22933 | (36.5) | 356588 | (25.6) | 379521 | (26.0) | 1.69 | (1.66 to 1.71) | |
| Episiotomy (yes)/perineal tear (yes) | 84 | (0.3) | 5473 | (0.4) | 522 | (0.8) | 5035 | (0.4) | 5557 | (0.4) | 2.68 | (2.46 to 2.92) | |
| Missing | 22 | 480 | 49 | 453 | 502 | ||||||||
| Anaesthesia† | |||||||||||||
| No/primary care medication | 13797 | (43.7) | 1075885 | (75.4) | 45774 | (72.8) | 1043908 | (74.8) | 1089682 | (74.8) | 1.00 | reference | |
| Opioid analgesics | 3449 | (10.9) | 104489 | (7.3) | 5939 | (9.4) | 101999 | (7.3) | 107938 | (7.4) | 1.28 | (1.24 to 1.31) | |
| Epidural during labour | 2892 | (9.2) | 77721 | (5.5) | 5219 | (8.3) | 75394 | (5.4) | 80613 | (5.5) | 1.27 | (1.24 to 1.31) | |
| Spinal or epidural at caesarean | 8795 | (27.9) | 151714 | (10.6) | 4970 | (7.9) | 155539 | (11.2) | 160509 | (11.0) | 0.75 | (0.73 to 0.77) | |
| General anaesthesia | 2627 | (8.3) | 16207 | (1.1) | 962 | (1.5) | 17872 | (1.3) | 18834 | (1.3) | 1.32 | (1.24 to 1.40) | |
Missing values of postpartum haemorrhage and pre-eclampsia are excluded
2test between pre-eclampsia and no pre-eclampsia, P ≤ 0.0001 X