Multivariable log-linear analyses: BIS in trying to cope with labour pain group versus a priori choice of labour analgesia group
| Planned vaginal birth, n=3628 (including caesarean deliveries) | Actual vaginal birth, n=3183 (excluding caesarean deliveries) | |||||||
| Antelabour-only confounders (30) | Antelabour plus intrapartum and postpartum confounders (43) | Antelabour-only confounders (30) | Antelabour plus intrapartum and postpartum confounders (49) | |||||
| Statistical parameter | RR (95% CI) | P value | RR (95% CI) | P value | RR (95% CI) | P value | RR (95% CI) | P value |
| A priori choice of analgesia | 0.65 (0.48 to 0.87) | 0.004 | 0.61 (0.45 to 0.83) | 0.002 | 0.59 (0.43 to 0.80) | 0.001 | 0.55 (0.38 to 0.75) | <0.001 |
| Nulliparous | 0.48 (0.41 to 0.56) | <0.001 | 0.52 (0.44 to 0.62) | <0.001 | 0.50 (0.43 to 0.59) | <0.001 | 0.53 (0.44 to 0.64) | <0.001 |
| Maternal age >90th percentile | 0.45 (0.33 to 0.61) | <0.001 | 0.50 (0.36 to 0.68) | <0.001 | 0.49 (0.35 to 0.67) | <0.001 | 0.51 (0.36 to 0.72) | <0.001 |
| Weight gain >90th percentile | 0.67 (0.53 to 0.85) | 0.001 | 0.68 (0.53 to 0.87) | 0.002 | 0.65 (0.50 to 0.84) | 0.01 | 0.64 (0.49 to 0.84) | 0.001 |
| Preterm newborn | 0.25 (0.17 to 0.37) | <0.001 | 0.57 (0.36 to 0.91) | 0.017 | 0.24 (0.15 to 0.36) | <0.001 | 0.60 (0.36 to 0.99) | 0.046 |
| BMI >90th percentile | 0.56 (0.43 to 0.73) | <0.001 | 0.63 (0.48 to 0.83) | 0.001 | 0.64 (0.48 to 0.85) | 0.002 | 0.72 (0.53 to 0.97) | 0.033 |
| Pregestational dysthyroidism | 0.72 (0.54 to 0.96) | 0.025 | 0.77 (0.55 to 0.99) | 0.046 | 0.70 (0.52 to 0.95) | 0.023 | ||
| Severe pre-eclampsia | 0.52 (0.32 to 0.86) | 0.011 | 0.55 (0.32 to 0.97) | 0.05 | ||||
| Neonatal weight <2500 g | 0.50 (0.33 to 0.75) | 0.001 | 0.48 (0.31 to 0.76) | 0.001 | ||||
| Neonatal weight ≥4000 g | 0.60 (0.43 to 0.83) | 0.002 | ||||||
| Lower maternal education | 0.82 (0.69 to 0.99) | 0.041 | ||||||
| Diabetes | 0.71 (0.56 to 0.91) | 0.007 | ||||||
| Smoking during pregnancy | 1.34 (1.00 to 1.79) | 0.048 | ||||||
| NICU admission | 0.24 (0.13 to 0.45) | <0.001 | 0.23 (0.12 to 0.47) | <0.001 | ||||
| Neonatal hypoglycaemia | 0.08 (0.04 to 0.16) | <0.001 | 0.07 (0.03 to 0.16) | <0.001 | ||||
| Phototherapy | 0.25 (0.16 to 0.3 8) | <0.001 | 0.23 (0.15 to 0.36) | <0.001 | ||||
| Haemorrhage >1000 mL | 0.64 (0.46 to 0.90) | 0.009 | 0.60 (0.42 to 0.86) | 0.006 | ||||
| Peripartum interventions | 0.51 (0.38 to 0.68) | <0.001 | 0.48 (0.36 to 0.66) | <0.001 | ||||
| Rooming-in | 1.95 (1.46 to 2.61) | <0.001 | 1.63 (1.11 to 2.38) | 0.012 | ||||
| Unplanned caesarean delivery | 0.62 (0.45 to 0.83) | 0.002 | ||||||
BIS, breastfeeding initiation success; BMI, body mass index; NICU, neonatal intensive care unit; RR, relative risk.
Nagelkerke’s coefficient of determination for the four analyses is 0.12, 0.224, 0.108, and 0.209 respectively.