Table 3

Proportions and associations of mode of birth outcomes, pain relief treatment and short–term maternal outcomes with induction of labour for non-medical reasons, stratified for gestational age groups 37–41 weeks, New South Wales, Australia 2001–2016 (N=474 652)

474 652 total births210 779 pimiparous births263 873 multiparous births
Spontaneous onset of labourInduction for non-medical reasonsTotal populationSpontaneous onset of labourInduction for non-medial reasonsAOR (99% CI)*Spontaneous onset of labourInduction for non-medical reasonsAOR (99% CI)*
Proportion n (%)Proportion n (%)AOR (99% CI)†Proportion n (%)Proportion n (%)Proportion n (%)Proportion n (%)
Mode of birth outcomes‡
Spontaneous vaginal birth
 37+0–37+614 322 (76.2)2400 (76.0)NA‡6081 (70.0)676 (54.5)NA‡8241 (81.6)1724 (89.9)NA‡
 38+0–38+642 781 (77.7)93 051 (75.1)NA‡15 779 (67.7)1861 (47.8)NA‡27 002 (85.1)7440 (87.7)NA‡
 39+0–39+693 809 (79.0)14 615 (72.2)NA‡33 074 (64.7)3422 (45.9)NA‡60 735 (89.7)11 193 (87.6)NA‡
 40+0–40+6120 671 (77.2)18 319 (63.5)NA‡42 385 (60.2)5602 (39.6)NA‡78 286 (95.0)12 717 (91.7)NA‡
 41+0–41+641 218 (73.2)2680 (56.2)NA‡15 464 (55.8)1096 (37.9)NA‡25 754 (90.0)1584 (84.2)NA‡
Instrumental vaginal birth
 37+0–37+62198 (11.7)383 (12.1)1.16 (0.99 to 1.37)1785 (20.5)295 (23.8) 1.50 (1.23 to 1.82) 413 (4.1)88 (4.6)1.00 (0.73 to 1.37)
 38+0–38+66322 (11.5)1689 (13.6) 1.51 (1.39 to 1.64) 4994 (21.4)1031 (26.5) 1.78 (1.59 to 1.99) 1328 (4.2)658 (7.8) 1.64 (1.44 to 1.87)
 39+0–39+615 040 (12.7)3019 (14.9) 1.48 (1.39 to 1.57) 12 089 (23.7)2033 (27.3) 1.57 (1.45 to 1.70) 2951 (4.4)986 (7.7) 1.69 (1.53 to 1.87)
 40+0–40+621 699 (13.9)5314 (18.4) 1.59 (1.52 to 1.67) 17 555 (25.0)4170 (29.5) 1.71 (1.61 to 1.81) 4144 (4.8)1144 (7.8) 1.58 (1.45 to 1.73)
 41+0–41+68253 (14.7)906 (19.0) 1.48 (1.32 to 1.66) 6880 (24.8)767 (26.5) 1.51 (1.33 to 1.72) 1373 (4.8)139 (7.4) 1.60 (1.26 to 2.04)
Caesarean section
 37+0–37+62265 (12.1)376 (11.9)1.00 (0.86 to 1.17)821 (9.5)270 (21.8) 3.13 (2.53 to 3.87) 1444 (14.3)106 (5.5) 0.34 (0.26 to 0.44)
 38+0–38+65923 (10.8)1392 (11.2) 1.11 (1.02 to 1.21) 2530 (10.9)1004 (25.8) 3.38 (3.00 to 3.80) 3393 (10.7)388 (4.6) 0.38 (0.33 to 0.44)
 39+0–39+69960 (8.4)2600 (12.8) 1.82 (1.71 to 1.94) 5952 (11.6)1999 (26.8) 3.13 (2.88 to 3.40) 4008 (5.9)601 (4.7) 0.80 (0.71 to 0.90)
 40+0–40+613 955 (8.9)5218 (18.1) 2.45 (2.33 to 2.58) 10 410 (14.8)4381 (31.0) 3.03 (2.85 to 3.22) 3545 (4.2)837 (5.7) 1.43 (1.29 to 1.59)
 41+0–41+66839 (12.1)1185 (24.8) 2.36 (2.13 to 2.62) 5346 (19.3)1027 (35.5) 2.60 (2.30 to 2.93) 1493 (5.2)158 (8.4) 1.71 (1.36 to 2.15)
Pain relief treatment§
No pain relief treatment
 37+0–37+63117 (16.6)272 (8.6)NA§809 (9.3)44 (3.5)NA§2308 (22.9)228 (11.9)NA§
 38+0–38+68956 (16.3)926 (7.5)NA§1627 (7.0)76 (2.0)NA§7329 (23.1)850 (10.0)NA§
 39+0–39+619 171 (16.1)1435 (7.1)NA§3230 (6.3)136 (1.8)NA§15 941 (23.5)1299 (10.2)NA§
 40+0–40+624 605 (15.7)1789 (6.2)NA§4177 (5.9)199 (1.4)NA§20 428 (23.8)1590 (10.8)NA§
 41+0–41+68052 (14.3)272 (5.7)NA§1402 (5.1)52 (1.8)NA§6650 (23.2)220 (11.7)NA§
Pharmacological medication
 37+0–37+610 174 (52.4)1382 (43.7) 1.70 (1.41 to 2.03) 5005 (57.6)422 (34.0) 1.56 (1.02 to 2.38) 5169 (51.2)960 (50.1) 1.82 (1.51 to 2.27)
 38+0–38+630 140 (54.8)5007 (40.4) 1.87 (1.70 to 2.07) 13 029 (55.9)1197 (30.7) 2.01 (1.47 to 2.76) 17 111 (53.9)3810 (44.9) 1.93 (1.74 to 2.15)
 39+0–39+666 722 (56.2)8084 (40.0) 1.87 (1.73 to 2.02) 27 688 (54.2)2115 (28.4) 1.87 (1.48 to 2.36) 39 034 (57.7)5969 (46.7) 1.89 (1.74 to 2.05)
 40+0–40+686 655 (55.4)11 029 (38.2) 1.87 (1.75 to 2.01) 35 552 (50.5)3605 (25.5) 2.18 (1.79 to 2.64) 51 103 (59.4)7424 (50.5) 1.87 (1.74 to 2.02)
 41+0–41+630 418 (54.0)1754 (36.8) 1.70 (1.43 to 2.02) 13 274 (47.9)739 (25.6) 1.52 (1.04 to 2.22) 17 144 (59.9)1015 (54.0) 1.80 (1.48 to 2.19)
Epidural anaesthesia
 37+0–37+65411 (28.8)1497 (47.4) 3.65 (3.03 to 4.39) 2846 (32.8)774 (62.4) 5.32 (3.50 to 8.08) 2565 (25.4)723 (37.7) 2.81 (2.27 to 3.48)
 38+0–38+615 702 (28.5)6430 (51.9) 4.79 (4.33 to 5.30) 8589 (36.9)2620 (67.2) 6.88 (5.03 to 9.41) 7113 (22.4)3810 (44.9) 4.21 (3.77 to 4.70)
 39+0–39+632 417 (27.3)10 680 (52.8) 5.42 (5.01 to 5.87) 20 073 (39.3)5196 (69.7) 6.13 (4.87 to 7.72) 12 344 (18.2)5484 (42.9) 5.08 (4.65 to 5.54)
 40+0–40+644 370 (28.4)15 991 (55.4) 5.35 (4.99 to 5.74) 30 449 (43.3)10 342 (73.1) 6.89 (5.70 to 8.34) 13 921 (16.2)5649 (38.4) 4.79 (4.42 to 5.19)
 41+0–41+617 527 (31.1)2733 (57.3) 4.35 (3.65 to 5.19) 12 939 (46.7)2094 (72.5) 4.23 (2.92 to 6.12) 4588 (16.0)639 (34.0) 4.11 (3.34 to 5.07)
Maternal outcomes¶
Episiotomy
 37+0–37+62843 (17.2)452 (16.2)1.15 (0.98 to 1.34)2158 (27.4)309 (31.8) 1.23 (1.01 to 1.49) 685 (7.9)143 (7.9)1.01 (0.79 to 1.31)
 38+0–38+68374 (17.1)1994 (18.1) 1.52 (1.40 to 1.64) 6078 (29.3)1091 (37.7) 1.55 (1.39 to 1.73) 2296 (8.1)903 (11.2) 1.42 (1.27 to 1.59)
 39+0–39+618 730 (17.2)3740 (21.2) 1.63 (1.54 to 1.73) 13 731 (30.4)2209 (40.5) 1.58 (1.46 to 1.70) 4999 (7.8)1531 (12.6) 1.66 (1.53 to 1.81)
 40+0–40+625 212 (17.7)6001 (25.4) 1.67 (1.60 to 1.75) 18 824 (31.4)4275 (43.7) 1.68 (1.59 to 1.78) 6388 (7.7)1726 (12.5) 1.62 (1.50 to 1.75)
 41+0–41+68590 (17.4)948 (26.4) 1.58 (1.4 2 to 1.77) 6780 (30.3)757 (40.6) 1.54 (1.36 to 1.76) 1810 (6.7)191 (11.1) 1.71 (1.38 to 2.11)
3rd/4th degree tear
 37+0–37+6340 (2.1)50 (1.8)1.10 (0.74 to 1.65)284 (3.6)44 (4.5)1.29 (0.84 to 1.99)56 (0.3)6 (0.3)0.44 (0.13 to 1.48)
 38+0–38+61136 (2.3)151 (1.4)0.83 (0.66 to 1.05)847 (4.1)117 (4.0)1.05 (0.81 to 1.38)289 (1.0)34 (0.4) 0.47 (0.29 to 0.75)
 39+0–39+62905 (2.7)316 (1.8) 0.85 (0.72 to 0.99) 2157 (4.8)227 (4.2)0.93 (0.77 to 1.02)748 (1.2)89 (0.7) 0.66 (0.49 to 0.89)
 40+0–40+64096 (2.9)524 (2.2) 0.79 (0.70 to 0.90) 3062 (5.1)400 (4.1) 0.82 (0.71 to 0.94) 1034 (1.3)124 (0.9) 0.71 (0.55 to 0.91)
 41+0–41+61696 (3.4)115 (3.2)0.84 (0.65 to 1.09)1279 (5.7)91 (4.9)0.84 (0.63 to 1.12)417 (1.5)24 (1.4)0.86 (0.49 to 1.50)
Vaginal repair
 37+0–37+610 467 (63.4)1649 (59.3)1.04 (0.92 to 1.16)6274 (79.8)810 (83.4)1.25 (0.98 to 1.58)4193 (48.5)839 (46.3)0.96 (0.83 to 1.10)
 38+0–38+631 954 (65.1)7043 (64.1) 1.25 (1.18 to 1.33) 17 198 (82.8)2538 (87.8) 1.62 (1.38 to 1.89) 14 756 (52.1)4505 (55.6) 1.17 (1.09 to 1.25)
 39+0–39+671 795 (66.0)11 952 (67.8) 1.29 (1.23 to 1.36) 38 253 (84.7)4858 (89.1) 1.51 (1.34 to 1.70) 33 542 (52.7)7094 (58.2) 1.24 (1.17 to 1.30)
 40+0–40+693 383 (65.6)17 056 (72.2) 1.37 (1.31 to 1.43) 50 740 (84.7)8841 (90.5) 1.68 (1.53 to 1.85) 42 643 (51.7)8215(59.3) 1.28 (1.22 to 1.35)
 41+0–41+632 805 (66.3)2669 (74.4) 1.36 (1.22 to 1.52) 19 049 (85.3)1663 (89.3) 1.40 (1.14 to 1.71) 13 756 (50.7)1006 (58.4) 1.34 (1.18 to 1.53)
Postpartum haemorrhage
 37+0–37+6210 (1.1)56 (1.8) 1.75 (1.18 to 2.59) 112 (1.3)28 (2.3) 1.81 (1.04 to 3.14) 98 (1.0)28 (1.5)1.72 (0.98 to 3.02)
 38+0–38+6581 (1.1)222 (1.8) 2.10 (1.70 to 2.59) 275 (1.2)95 (2.4) 2.33 (1.70 to 3.19) 306 (1.0)127 (1.5) 1.94 (1.46 to 2.58)
 39+0–39+61299 (1.1)352 (1.7) 1.85 (1.57 to 2.17) 705 (1.4)167 (2.2) 1.73 (1.38 to 2.17) 594 (0.9)185 (1.4) 2.01 (1.60 to 2.52)
 40+0–40+62114 (1.4)534 (1.9) 1.47 (1.29 to 1.67) 1156 (1.6)324 (2.3) 1.45 (1.23 to 1.72) 958 (1.1)210 (1.4) 1.50 (1.23 to 1.83)
 41+0–41+6907 (1.6)123 (2.6) 1.58 (1.23 to 2.04) 526 (1.9)86 (3.0) 1.57 (1.16 to 2.14) 381 (1.3)37 (2.0) 1.61 (1.02 to 2.52)
  • Associations in bold are statistically significant p≤0.01.

  • *Multinominal and multivariate logistic regression models were adjusted for maternal age, country of birth, socioeconomic status.

  • †Multinominal and multivariate logistic regression models were adjusted for maternal age, country of birth, socioeconomic status, parity.

  • ‡In the multinominal regression model vaginal birth is the reference group.

  • §In the multinomial regression model no pain relief treatment is the reference group.

  • ¶The maternal outcomes episiotomy, third/fourth degree tear, vaginal repair are calculated for vaginal births for the total population (n=424 939), first births (n=177 039) and 2nd–8th births (n=247 900).

  • aOR, adjusted OR; NA, not aaplicable.