Table 1

Maternal, birth and infant characteristics of the included population, stratified for spontaneous onset of labour and induction of labour for non-medical reasons, New South Wales, Australia, 2001–2016 (N=474 652)

474 652 infants210 779 infants primiparous births263 873 infants multiparous births
Total populationSpontaneous onset of labourInduction of labour for non-medical reasonsTotal infantsSpontaneous onset of labourInduction of labour for non-medical reasonsTotal infantsSpontaneous onset of labourInduction of labour for non-medical reasons
N=474 652n=405 255n=69 397n=210 779n=181 145n=29 634n=263 873n=224 110n=39 763
100%85.40%14.60%100%85.90%14.10%100%84.90%15.10%
N (%)n (%)n (%)n (%)n (%)n (%)n (%)n (%)n (%)
Maternal characteristics*
Maternal age (years)
 20–2597 687 (20.6)87 302 (21.5)10 385 (15.0)55 632 (26.4)49 598 (27.4)6034 (20.4)42 055 (15.9)37 704 (16.8)4351 (10.9)
 26–30187 391 (39.5)160 149 (39.5)27 242 (39.3)89 530 (42.5)76 466 (42.2)13 064 (44.1)97 861 (37.1)83 683 (37.3)14 178 (35.7)
 31–35189 574 (39.9)157 804 (38.9)31 770 (45.8)65 617 (31.1)55 081 (30.4)10 536 (35.6)123 957 (47.0)102 723 (45.8)21 234 (53.4)
Country of birth
 Australia289 182 (60.9)241 138 (59.5)480 44 (69.2)122 912 (58.3)104 568 (57.7)18 344 (61.9)166 270 (63.0)136 570 (60.9)29 700 (74.7)
 Not Australia183 707 (38.7)162 623 (40.1)21 084 (30.4)86 864 (41.2)75 727 (41.8)11 137 (37.6)96 843 (36.7)86 896 (38.8)9947 (25.0)
 Missing1763 (0.4)1494 (0.4)269 (0.4)1003 (0.5)850 (0.5)153 (0.5)760 (0.3)644 (0.3)116 (0.3)
Socioeconomic status†
 Low120 425 (25.4)105 885 (26.1)14 540 (21.0)45 534 (21.6)40 155 (22.2)5379 (18.2)74 891 (28.4)65 730 (29.3)9161 (23.0)
 Middle159 480 (33.6)137 611 (34.0)21 869 (31.5)67 714 (32.1)58 535 (32.3)9179 (31.0)91 766 (34.8)79 076 (35.3)12 690 (31.9)
 High189 730 (40.0)157 271 (38.8)32 459 (46.8)94 925 (45.0)80 146 (44.2)14 779 (49.9)94 805 (35.9)77 125 (34.4)17 680 (44.5)
 Missing5017 (1.1)4488 (1.1)529 (0.8)2606 (1.2)2309 (1.3)297 (1.0)2411 (0.9)2179 (1.0)232 (0.6)
Gestation (weeks)
 37+0–37+621 944 (4.6)18 785 (4.6)3159 (4.6)9928 (4.7)8687 (4.8)1241 (4.2)12 016 (4.6)10 098 (4.5)1918 (4.8)
 38+0–38+667 408 (14.2)55 026 (13.6)12 382 (17.8)27 199 (12.9)23 303 (12.9)3896 (13.1)40 209 (15.2)31 723 (14.2)8486 (21.3)
 39+0–39+6139 043 (29.3)118 809 (29.3)20 234 (29.2)58 569 (27.8)51 115 (28.2)7454 (25.2)80 474 (30.5)67 694 (30.2)12 780 (32.1)
 40+0–40+6185 176 (39.0)156 325 (38.6)28 851 (41.6)84 503 (40.1)70 350 (38.8)14 153 (47.8)100 673 (38.2)85 975 (38.4)14 698 (37.0)
 41+0–41+661 081 (12.9)56 310 (13.9)4771 (6.9)30 580 (14.5)27 690 (15.3)2890 (9.8)30 501 (11.6)28 620 (12.8)1881 (4.7)
Mode of birth characteristics
Mode of birth
 Vaginal360 116 (75.9)312 801 (77.2)47 315 (68.2)125 440 (59.5)112 783 (62.3)12 657 (42.7)234 676 (88.9)200 018 (89.2)34 658 (87.2)
 Instrumental64 823 (13.7)53 512 (13.2)11 311 (16.3)51 599 (24.5)43 303 (23.9)8296 (28.0)13 224 (5.0)10 209 (4.6)3015 (7.6)
 Caesarean section49 713 (10.5)38 942 (9.6)10 771 (15.5)33 740 (16.0)25 059 (13.8)8681 (29.3)15 973 (6.1)13 883 (6.2)2090 (5.3)
Pain medication
 None68 595 (14.5)63 901 (15.8)4694 (6.8)11 752 (5.6)11 245 (6.2)507 (1.7)56 843 (21.5)52 656 (23.5)4187 (10.5)
 Pharmacological medication‡251 365 (53.0)224 109 (55.3)27 256 (39.3)102 626 (48.7)94 548 (52.2)8078 (27.3)148 739 (56.4)129 561 (57.8)19 178 (48.2)
 Epidural/Spinal analgesia152 758 (32.2)115 427 (28.5)37 331 (53.8)95 922 (45.5)74 896 (41.3)21 026 (71.0)56 836 (21.5)40 531 (18.1)16 305 (41.0)
 Missing1934 (0.4)1818 (0.4)116 (0.2)479 (0.2)456 (0.3)23 (0.1)1455 (0.6)1362 (0.6)93 (0.2)
Infant characteristics
Gender
 Female234 907 (49.5)201 081 (49.6)33 826 (48.7)104 349 (49.5)89 930 (49.6)14 419 (48.7)130 558 (49.5)111 151 (49.6)19 407 (48.8)
 Male239 623 (50.5)204 086 (50.4)35 537 (51.2)106 370 (50.5)91 166 (50.3)15 204 (51.3)133 253 (50.5)112 920 (50.4)20 333 (51.1)
 Missing122 (0.03)88 (0.02)34 (0.05)60 (0.03)49 (0.03)11 (0.04)62 (0.02)39 (0.02)23 (0.06)
Birth weight (grams)
 ≤150029 (0.006)26 (0.006)3 (0.004)8 (0.004)8 (0.004)0 (0)21 (0.008)18 (0.008)3 (0.008)
 1501–25003987 (0.8)3577 (0.9)410 (0.6)2414 (1.1)2156 (1.2)258 (0.9)1573 (0.6)1421 (0.6)152 (0.4)
 2501–3500249 078 (52.5)215 601 (53.2)33 477 (48.2)123 832 (58.7)108 235 (59.8)15 597 (52.6)125 246 (47.5)107 366 (47.9)17 880 (45.0)
 3501–4500214 478 (45.2)180 315 (44.5)34 163 (49.2)82 584 (39.2)69 252 (38.2)13 332 (45.0)131 894 (50.0)111 063 (49.6)20 831 (52.4)
 ≥45016968 (1.5)5635 (1.4)1333 (1.9)1894 (0.9)1452 (0.8)442 (1.5)5074 (1.9)4183 (1.9)891 (2.2)
 Missing122 (0.02)101 (0.02)11 (0.02)47 (0.02)42 (0.02)5 (0.02)65 (0.02)59 (0.03)6 (0.02)
  • *Women who were induced for non- medical reasons differed statistically significantly on all maternal, birth and child characteristics (p≤0.001).

  • †Pharmacological pain medication (ie, nitrous oxide, systematic opioid, local administered to perineum, pudendal, morphine and pethidine—other than epidural analgesia).Socioeconomic status are index data of relative socioeconomic advantage and disadvantage, low (deciles 0–3), middle (deciles 4–6), high (7–10 deciles).

  • ‡Socioeconomic status are index data of relative socioeconomic advantage and disadvantage, low (deciles 0–3), middle (deciles 4–6), high (7–10 deciles).