Table 2 Predictive factors for planned repeat caesarean section, NSW, 2007–2011. Two models were fitted progressively adjusting for case-mix and hospital factors
Variable and categories | Case-mix model | Hospital model |
|---|---|---|
OR (95Â % CI) | OR (95Â % CI) | |
Maternal age (years) | 1.02 (1.02, 1.03) | 1.02 (1.02, 1.03) |
Country of birth | Â | Â |
 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 | Â | Â |
 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 12Â months) | 0.81 (0.72, 0.91) | 0.81 (0.71, 0.91) |
Inter-pregnancy interval (months) | Â | Â |
 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) | Â | Â |
 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 | - | Â |
 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) |