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Table 1 Case-mix characteristics of the study population, NSW, 2007–2011. The study population consists of multiparous women with a singleton cephalic-presenting infant at ≥37 weeks gestation with at least one previous caesarean section

From: Variation in hospital caesarean section rates for women with at least one previous caesarean section: a population based cohort study

Variables and levels   All deliveries Any repeat caesareana Planned repeat CS Intrapartum repeat CS Vaginal birth after caesarean Planned vaginal birthb
   N=61894 (column %) N = 50819 (column %) N=45006 (column %) N=5813 (column %) N = 11075 (column %) N=16888 (column %)
Maternal age Under 20 314 (0.5) 248 (0.5) 211 (0.5) 37 (0.6) 66 (0.6) 103 (0.6)
  20 to 34 36626 (59.2) 29472 (58.0) 25843 (57.4) 3629 (62.4) 7154 (64.6) 10783 (63.9)
  35+ 24954 (40.3) 21099 (41.5) 18952 (42.1) 2147 (36.9) 3855 (34.8) 6002 (35.5)
Country of birth Australia or New Zealand 45012 (72.9) 37018 (73.0) 32947 (73.4) 4071 (70.2) 7994 (72.3) 12065 (71.6)
  Europe or North America 3554 (5.8) 2921 (5.8) 2575 (5.7) 346 (6.0) 633 (5.7) 979 (5.8)
  Other 13177 (21.3) 10750 (21.2) 9368 (20.9) 1382 (23.8) 2427 (22.0) 3809 (22.6)
Model of care Public patient in public hospital 36059 (58.2) 28020 (55.1) 24079 (53.5) 3941 (67.8) 8039 (72.6) 11980 (70.9)
  Private patient in public hospital 5544 (9.0) 4667 (9.2) 4201 (9.3) 466 (8.0) 877 (7.9) 1343 (8.0)
  Private patient in private hospital 20291 (32.8) 18132 (35.7) 16726 (37.2) 1406 (24.2) 2159 (19.5) 3565 (21.1)
Smoking in pregnancy 6174 (10.0) 4599 (9.1) 3947 (8.8) 652 (11.2) 1575 (14.2) 2227 (13.2)
Diabetes (pre-existing or gestational) 5233 (8.5) 4598 (9.0) 4166 (9.3) 432 (7.4) 635 (5.7) 1067 (6.3)
Hypertensive disorders 3327 (5.4) 2842 (5.6) 2510 (5.6) 332 (5.7) 485 (4.4) 817 (4.8)
Other chronic medical conditionsc 788 (1.3) 709 (1.4) 625 (1.4) 84 (1.4) 79 (0.7) 163 (1.0)
Parity 2 or more (compared to parity 1) 23911 (38.7) 18516 (36.5) 17132 (38.2) 1384 (23.8) 5395 (48.8) 6779 (40.2)
2 or more previous caesarean sections 13554 (22.0) 13353 (26.4) 12831 (28.6) 522 (9.0) 201 (1.9) 723 (4.3)
Labour/vaginal birth prior to first caesarean 5819 (9.4) 3851 (7.6) 3383 (7.5) 468 (8.1) 1968 (17.8) 2436 (14.4)
Previous vaginal birth after caesarean 4130 (6.7) 1121 (2.2) 834 (1.9) 287 (4.9) 3009 (27.2) 3296 (19.5)
Previous 3rd or 4th degree perineal tear 551 (0.9) 402 (0.8) 372 (0.8) 30 (0.5) 149 (1.3) 179 (1.1)
Previous perinatal death 1000 (1.6) 825 (1.6) 752 (1.7) 73 (1.3) 175 (1.6) 248 (1.5)
Non-CS uterine scar 421 (0.7) 403 (0.8) 377 (0.8) 26 (0.4) 18 (0.2) 44 (0.3)
Assisted reproductive technology use, last 12 months 1914 (3.1) 1594 (3.1) 1447 (3.2) 147 (2.5) 320 (2.9) 467 (2.8)
Inter-pregnancy interval (months) 0-17 21126 (34.1) 17082 (33.6) 15136 (33.6) 1946 (33.5) 4044 (36.5) 5990 (35.5)
  18-59 27761 (44.9) 23069 (45.4) 20617 (45.8) 2452 (42.2) 4692 (42.4) 7144 (42.3)
  60+ 4903 (7.9) 4066 (8.0) 3605 (8.0) 461 (7.9) 837 (7.6) 1298 (7.7)
  Unknown 8104 (13.1) 6602 (13.0) 5648 (12.5) 954 (16.4) 1502 (13.6) 2456 (14.5)
Placental conditionsd 1079 (1.7) 990 (1.9) 807 (1.8) 183 (3.1) 89 (0.8) 272 (1.6)
Gestational age (weeks) 37 4597 (7.4) 3870 (7.6) 3320 (7.4) 550 (9.5) 727 (6.6) 1277 (7.6)
  38 19452 (31.4) 17579 (34.6) 16389 (36.4) 1190 (20.5) 1873 (16.9) 3063 (18.1)
  39 25143 (40.6) 21915 (43.1) 20366 (45.3) 1549 (26.6) 3228 (29.1) 4777 (28.3)
  40 9016 (14.6) 5367 (10.6) 3782 (8.4) 1585 (27.3) 3649 (32.9) 5234 (31.0)
  41+ 3686 (6.0) 2088 (4.1) 1149 (2.6) 939 (16.2) 1598 (14.4) 2537 (15.0)
Birth weight for gestational age Small (<10th percentile) 5,501 (8.9) 4110 (8.1) 3501 (7.8) 609 (10.5) 1391 (12.6) 2000 (11.8)
  Appropriate 49453 (79.9) 40540 (79.8) 35962 (79.9) 4578 (78.8) 8913 (80.5) 13491 (79.9)
  Large (>90th percentile) 6927 (11.2) 6158 (12.1) 5533 (12.3) 625 (10.8) 769 (6.9) 1394 (8.3)
Stillbirth 60 (0.1) 30 (0.1) 23 (0.1) 7 (0.1) 30 (0.3) 37 (0.2)
Severe maternal morbidity 654 (1.9) 526 (1.9) 395 (1.6) 131 (4.0) 128 (2.1) 259 (2.8)
Severe neonatal morbidity 1275 (2.1) 1058 (2.1) 851 (1.9) 207 (3.6) 217 (2.0) 424 (2.5)
Postpartum haemorrhage 2847 (4.6) 1666 (3.3) 1301 (2.9) 365 (6.3) 1181 (10.7) 1546 (9.2)
Apgar score at five minutes <7 520 (0.8) 371 (0.7) 261 (0.6) 110 (1.9) 149 (1.4) 259 (1.5)
  1. CS = caesarean section
  2. aIncludes planned repeat CS and intrapartum repeat CS
  3. bIncludes intrapartum repeat caesarean section and vaginal birth after caesarean section
  4. cIncluded renal, cardiac, asthma/COPD, autoimmune, thyroid and inflammatory bowel disease
  5. dIncluded morbidly adherent placenta, placental abruption, placenta praevia, antepartum haemorrhage