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Table 3 Predictive factors for intrapartum caesarean section among women with a trial of labour for a planned vaginal birth, NSW, 2007–2011. Two models were fitted progressively adjusting for case-mix and hospital factors

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

Variable and categories Case-mix model Hospital model
OR (95 % CI) OR (95 % CI)
Maternal age (years) 1.02 (1.01, 1.03) 1.02 (1.02, 1.03)
Country of birth   
 Australia or New Zealand 1.00 1.00
 Europe or North America 0.86 (0.74, 1.00) 0.86 (0.74, 1.00)
 Other 1.17 (1.06, 1.29) 1.17 (1.06, 1.29)
Smoking 1.15 (1.03, 1.29) 1.14 (1.02, 1.29)
Diabetes (pre-existing or gestational) 1.27 (1.10, 1.46) 1.27 (1.10, 1.46)
Hypertensive disorders 1.31 (1.12, 1.53) 1.31 (1.12, 1.53)
Other chronic medical conditionsa 1.95 (1.38, 2.73) 1.93 (1.37, 2.71)
Parity 2 or more (versus parity 1) 0.70 (0.63, 0.78) 0.70 (0.63, 0.78)
Labour/vaginal birth prior to index caesarean 0.48 (0.42, 0.56) 0.48 (0.42, 0.55)
Previous vaginal birth after caesarean 0.16 (0.14, 0.19) 0.16 (0.14, 0.19)
Previous perinatal death 1.80 (1.32, 2.46) 1.79 (1.31, 2.44)
Non-CS uterine scar 2.78 (1.41, 5.48) 2.75 (1.39, 5.44)
Assisted reproductive technology use (last 12 months) 0.55 (0.44, 0.68) 0.55 (0.45, 0.68)
Inter-pregnancy interval (months)   
 0-17 0.92 (0.85, 1.00) 0.92 (0.85, 1.00)
 18-59 1.00 1.00
 60+ 1.22 (1.06, 1.40) 1.21 (1.06, 1.40)
 Unknown 0.83 (0.74, 0.92) 0.82 (0.74, 0.92)
Placental conditionsb 4.26 (3.22, 5.65) 4.26 (3.22, 5.65)
Estimated gestational age (weeks)   
 37 1.58 (1.37, 1.82) 1.58 (1.38, 1.82)
 38 1.30 (1.18, 1.44) 1.30 (1.18, 1.45)
 39 1.00 1.00
 40 0.94 (0.86, 1.03) 0.94 (0.86, 1.03)
 41+ 1.41 (1.26, 1.58) 1.41 (1.26, 1.57)
Large for gestational age (>90th percentile) 1.71 (1.53, 1.90) 1.71 (1.53, 1.91)
Stillbirth 0.26 (0.11, 0.62) 0.25 (0.10, 0.62)
Repeat caesarean rate after nulliparous breech caesarean (Propensity towards vaginal birth after caesarean section) - 1.04 (1.02, 1.07)
Instrumental delivery rate - 0.82 (0.71, 0.93)
  1. aIncluded renal, cardiac, asthma/COPD, autoimmune, thyroid and inflammatory bowel disease
  2. bIncluded morbidly adherent placenta, placental abruption, placenta praevia, antepartum haemorrhage