Table 2.
Derivation and internal refinement multivariable regression odds estimates for cesarean delivery
| Derivation Cohort | Internal Refinement Cohort | |||
|---|---|---|---|---|
| Characteristic | Adjusted OR (95% CI) | P value | Adjusted OR (95% CI) | P value |
| Nulliparous | 7.84 (4.33–14.20) | <0.001 | 3.77(2.01–7.06) | <0.001 |
| GA ≥ 40 weeks | 3.22 (1.99–5.21) | <0.001 | 1.28 (0.77–2.12) | 0.33a |
| BMI category before deliveryb | 1.42 (1.17–1.74) | <0.001 | 1.50 (1.22–1.86) | <0.001 |
| Height categoryc | 1.29 (1.04–1.61) | 0.02 | 1.38 (1.09–1.74) | 0.007 |
| Modified Bishop at induction | 0.80 (0.69–0.94) | 0.008 | 0.82 (0.70–0.96) | 0.01 |
| AUC | 0.79 (0.74–0.83) | 0.73 (0.67–0.78) | ||
Abbreviations: OR, odds ratio; CI, confidence interval; GA, gestational age; BMI, body mass index
In the internal refinement set, gestational age ≥ 40 weeks did not reach statistical significance, but was retained since gestational age is known to be a risk factor for cesarean delivery.
BMI was separated into normal (<25.0 kg/m2), overweight (25.0–29.9 kg/m2), Obesity- Class 1 (30.0–34.9 kg/m2), Obesity-Class 2 (35.0–39.9 kg/m2), Obesity-Class 3 (≥40.0 kg/m2), and entered as an ordinal variable with BMI <25.0 kg/m2 used as the reference (e.g. from normal weight to overweight and then from overweight to obese) there was a 42% increase in risk of cesarean).
Height was reverse coded (decreasing height associated with increasing risk), categorized into (<62.0″, 62.0″–63.9″, 64.0″–65.9″, ≥66″), and entered as an ordinal variable