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Table 2 Predictive factors for planned repeat caesarean section, 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 (1.02, 1.03) 1.02 (1.02, 1.03)
Country of birth   
 Australia or New Zealand 1.00 1.00
 Europe or North America 0.83 (0.76, 0.91) 0.83 (0.76, 0.91)
 Other 0.87 (0.82, 0.93) 0.88 (0.83, 0.93)
Smoking 0.91 (0.85, 0.98) 0.92 (0.85, 0.99)
Socio-economic statusa   
 1st quintile (high) 1.27 (1.14, 1.42) 1.28 (1.15, 1.43)
 2nd quintile 1.17 (1.06, 1.30) 1.18 (1.07, 1.31)
 3rd quintile 1.18 (1.07, 1.30) 1.18 (1.07, 1.30)
 4th quintile 1.01 (0.93, 1.10) 1.01 (0.93, 1.10)
 5th quintile (low) 1.00 1.00
Diabetes (pre-existing or gestational) 1.27 (1.17, 1.38) 1.28 (1.18, 1.39)
Hypertensive disorders 1.10 (1.00, 1.21) 1.11 (1.01, 1.22)
Other chronic medical conditionsb 1.42 (1.16, 1.74) 1.43 (1.17, 1.74)
Placental conditionsc 1.11 (0.94, 1.30) 1.11 (0.94, 1.30)
Parity 2 or more (versus parity 1) 2.09 (1.97, 2.22) 2.10 (1.98, 2.22)
Labour/vaginal birth prior to index caesarean 0.28 (0.26, 0.31) 0.28 (0.26, 0.31)
Previous vaginal birth after caesarean 0.05 (0.04, 0.05) 0.05 (0.04, 0.05)
Previous 3rd or 4th degree perineal tear 2.44 (1.93, 3.07) 2.44 (1.93, 3.07)
Previous perinatal death 2.66 (2.20, 3.21) 2.66 (2.20, 3.20)
Non-CS uterine scar 2.20 (1.55, 3.12) 2.21 (1.56, 3.13)
Assisted reproductive technology use (last 12 months) 0.81 (0.72, 0.91) 0.81 (0.71, 0.91)
Inter-pregnancy interval (months)   
 0-17 0.90 (0.86, 0.95) 0.90 (0.86, 0.95)
 18-59 1.00 1.00
 60+ 1.05 (0.96, 1.14) 1.05 (0.96, 1.14)
 Unknown 0.69 (0.64, 0.73) 0.69 (0.64, 0.73)
Estimated gestational age (weeks)   
 37 0.57 (0.52, 0.62) 0.57 (0.52, 0.62)
 38 1.14 (1.08, 1.21) 1.14 (1.08, 1.21)
 39 1.00 1.00
 40 0.18 (0.17, 0.20) 0.18 (0.17, 0.20)
 41+ 0.14 (0.12, 0.15) 0.14 (0.12, 0.15)
Small for gestational age (<10th percentile) 0.77 (0.71, 0.84) 0.77 (0.71, 0.84)
Large for gestational age (>90th percentile) 1.47 (1.38, 1.57) 1.47 (1.38, 1.57)
Stillbirth 0.24 (0.13, 0.46) 0.25 (0.13, 0.46)
Repeat caesarean rate after nulliparous breech caesarean (Propensity towards vaginal birth after caesarean section) - 0.95 (0.93, 0.96)
Oxytocin induction and/or augmentation for women with previous caesarean - 0.95 (0.90, 1.01)
Low risk rate among all birth - 1.18 (1.05, 1.32)
Level of hospital care -  
 Public with primary training   1.00
 Public with secondary training - 1.30 (0.91, 1.85)
 Public, other - 1.28 (0.89, 1.82)
 Private - 1.80 (1.24, 2.61)
  1. aIndex of Education and Occupation published by the Australian Bureau of Statistics based on postcode [27]
  2. bIncluded renal, cardiac, asthma/c obstructive pulmonary, autoimmune, thyroid and inflammatory bowel disease
  3. cIncluded morbidly adherent placenta, placental abruption, placenta praevia, antepartum haemorrhage