Table 3.
Risk of cesarean by measures of the midpelvis
| Exposure Group | Number Cesarean* (n, %) | RR (95% CI) | AOR† (95% CI) | p | |
|---|---|---|---|---|---|
| Transverse Diameter | <10th (≤9.0 cm) (n=77) | 35 (45.5%) | 1.7 (1.3–2.3) | 2.0 (1.0–3.8) | 0.04 |
| >10th (>9.0 cm) (n=349) | 92 (26.3%) | Ref | Ref | ||
| <5th (≤8.0 cm) (n=24) | 13 (54.2%) | 1.9 (1.3–2.8) | 2.0 (0.7–5.5) | 0.19 | |
| >5th (>8.0 cm) (n=402) | 114 (28.4)%) | Ref | Ref | ||
| Anteroposterior Diameter | <10th (≤9.5 cm) (n=51) | 50 (98.0%) | 4.8 (3.9–5.8) | 112.7 (14.9–854.1) | <0.01 |
| >10th (>9.5 cm) (n=375) | 77 (20.5%) | Ref | Ref | ||
| <5th (≤9.0 cm) (n=28) | 28 (100%) | 4.0 (3.4–4.8) | - | - | |
| >5th (>9.0 cm) (n=398) | 99 (24.9%) | Ref | - | ||
| Circumference | <10th (≤29.8 cm) (n=47) | 41 (87.2) | 3.8 (3.1–4.8) | 19.3 (6.9–53.6) | <0.01 |
| >10th (>29.8 cm) (n=379) | 86 (22.7%) | Ref | Ref | ||
| <5th (≤29.0 cm) (n=20) | 19 (95.0%) | 3.6 (3.0–4.3) | - | - | |
| >5th (>29.0 cm) (n=406) | 108 (26.7%) | Ref | - |
*
The percentage of cesarean deliveries represents the positive predictive value (<10th, <5th) or the negative predictive value (>10th, >5th) of the pelvic measurement.
†
Adjusted for prior cesarean delivery, labor induction
-Adjusted analysis not performed