Table 2

The association between mode of delivery in subgroups and combined adverse maternal and neonatal outcomes by generalised estimated equation model

Modified classification of caesarean
groups* (N, %)
WAOSUnadjusted modelAdjusted model†
Meanβ (95% CI)β (95% CI)
Group NS (37 841, 20%)
 Intrapartum CD (5582, 15%)7.162.72 (1.81 to 3.64)0.14 (−0.71 to 1.00)
 Vaginal delivery (32 259, 85%)4.44Ref.Ref.
Group NI (30 892, 16%)
 Intrapartum CD (9686, 31%)5.040.18 (−1.04 to 1.39)−0.55 (−1.16 to 0.06)
 Vaginal delivery (21 206, 69%)4.86Ref.Ref.
Group NC (2851, 1.5%)
 Pre-labour CD (2851, 100%)7.10
 Vaginal delivery (0, 0%)
Group MS (42 272, 22%)
 Intrapartum CD (1365, 3%)7.834.81 (3.39 to 6.23)1.73 (0.23 to 3.23)
 Vaginal delivery (40907, 97%)3.02Ref.Ref.
Group MI (28 973, 15%)
 Intrapartum CD (2019, 7%)7.023.57 (2.14 to 4.99)1.95 (0.50 to 3.40)
 Vaginal delivery (26 954, 93%)3.45Ref.Ref.
Group MC (1403, 0.7%)
 Pre-labour CD (1403, 100%)9.34
 Vaginal delivery (0, 0%)
Group PC (overall) (17 289, 8.9%)
 Pre-labour CD (10 958, 63%)4.830.96 (-0.03 to 1.94)1.03 (0.03 to 2.03)
 Intrapartum CD (2353, 14%)5.581.70 (0.37 to 3.03)1.30 (0.28 to 2.32)
 Vaginal delivery (3978, 23%)3.88Ref.Ref.
Group PC (prior number of CS=1) (12 292, 6.3%)
  Pre-labour CD (6738, 55%)4.670.84 (−0.20 to 1.88)1.06 (−0.04 to 2.17)
  Intrapartum CD (1732, 14%)5.790.76 (0.47 to 3.43)1.38 (0.30 to 2.46)
  Vaginal delivery (3822, 31%)3.84Ref.Ref.
Group PC (prior number of CS≥2) (4997, 2.6%)
  Pre-labour CD (4220, 85%)4.900.19 (−1.86 to 2.24)0.01 (−1.67 to 1.70)
  Intrapartum CD (621, 12%)5.090.10 (−1.94 to 2.15)0.50 (−0.90 to 1.90)
  Vaginal delivery (156, 3%)5.01Ref.Ref.
Group BR (overall) (7879, 4.1%)
 Pre-labour CD (5665, 72%)21.08−38.07 (−79.31 to 3.18)−27.90 (−49.41 to −6.40)
 Intrapartum CD (1582, 20%)25.83−33.31 (−73.91 to 7.30)−23.85 (−44.02 to −3.67)
 Vaginal delivery (632, 8%)59.14Ref.Ref.
Group BR (breech) (7628, 4.0%)‡
  Pre-labour CD (5467, 72%)20.99−36.75 (−77.17 to 3.67)−28.31 (−48.76 to −7.86)
  Intrapartum CD (1529, 20%)25.64−32.10 (−70.86 to 6.66)−24.71 (−43.56 to −4.87)
  Vaginal delivery (632, 8%)57.74Ref.Ref.
  Group preterm BR (breech) (2512, 1.3%)‡
   Pre-labor CD (1714, 68%)55.04−93.92 (−133.79 to 54.06)−90.49 (−133.58 to −47.40)
   Intrapartum CD (566, 23%)59.30−89.66 (−125.67 to 53.66)−80.36 (−121.33 to −39.39)
   Vaginal delivery (232, 9%)148.97Ref.Ref.
  Group term BR (breech) (5116, 2.7%)‡
   Pre-labour CD (3753, 73%)5.430.61 (−2.80 to 4.02)0.88 (−2.62 to 4.37)
   Intrapartum CD (963, 19%)5.851.03 (−1.98 to 4.03)0.41 (−2.69 to 3.50)
   Vaginal delivery (400, 8%)4.83Ref.Ref.
Group BR (transverse or oblique) (251, 0.1%)
  Pre-labour CD (198, 79%)23.54
  Intrapartum CD (53, 21%)31.51
  Vaginal delivery (0, 0%)
Group TW (overall) (4723, 2.4%)
 Pre-labour CD (2391, 51%)27.88−2.05 (−6.58 to 2.48)−4.89 (−9.55 to −0.23)
 Intrapartum CD (835, 18%)32.172.25 (−3.24 to 7.74)−4.89 (−8.58 to −1.19)
 Vaginal delivery (1497, 31%)29.93Ref.Ref.
Group preterm TW (3256, 1.7%)
  Pre-labor CD (1625, 50%)38.10−2.82 (10.22 to 4.58)−7.53 (−14.62 to −0.45)
  Intrapartum CD (646, 20%)39.23−1.68 (−8.68 to 5.31)−6.23 (−11.51 to −0.94)
  Vaginal delivery (985, 30%)40.92Ref.Ref.
  Preterm with first twin in cephalic presentation (1821, 0.9%)
   Pre-labour CD (682, 37%)40.565.91 (−0.64 to 12.46)−2.55 (−8.03 to 2.93)
   Intrapartum CD (346, 19%)36.601.94 (−5.00 to 8.89)−0.33 (−5.63 to 4.97)
   Vaginal delivery (793, 44%)34.66Ref.Ref.
  Preterm with first twin in non-cephalic presentation (1435, 0.7%)
   Pre-labour CD (943, 66%)36.30−28.78 (−65.00 to 7.43)−20.77 (−48.26 to 6.71)
   Intrapartum CD (300, 21%)42.42−22.67 (−55.10 to 9.77)−20.00 (−43.06 to −0.95)
   Vaginal delivery (192, 13%)65.09Ref.Ref.
Group term TW (1467, 0.8%)
  Pre-labour CD (766, 52%)5.15−3.15 (−6.44 to 0.13)−1.55 (−4.94 to 1.84)
  Intrapartum CD (189, 13%)7.12−1.18 (−5.88 to 3.52)−1.68 (−5.10 to 1.74)
  Vaginal delivery (512, 35%)8.30Ref.Ref.
Group PT (19444, 10%)
 Pre-labour CD (3282, 17%)42.6115.67 (10.08 to 21.27)2.98 (−1.04 to 7.00)
 Intrapartum CD (2706, 14%)31.334.40 (−2.53 to 11.33)−0.85 (−5.90 to 4.19)
 Vaginal delivery (13 456, 69%)26.93Ref.Ref.
  • *The new labelling system corresponds well with the previous numbering system as follows: 1=NS (Nulliparous, Spontaneous); 2a=NI (Nulliparous, Induced); 2b=NC (Nulliparous, Caesarean); 3=MS (Multiparous, Spontaneous); 4a=MI (Multiparous, Induced); 4b=MC (Multiparous, Caesarean); 5=PC (Previous Caesarean); 6,7,9 combined=BR (BReech and other non-cephalic presentation); 8=TW (Twin and other multiple pregnancies); 10=PT (PreTerm).

  • †Adjusted model: adjusted for a number of potential confounders (online supplementary table S1) wherever appropriate.

  • ‡Transverse and oblique lies were deleted in the regression analysis because these are the hard indication for CD. It should be 100% CD.

  • CD, caesarean delivery.