Table 4. Performance of accelerated 28–36 week fetal growth velocities (>30 EFW/AC centiles) and 36-week ultrasound EFW >95th centile in predicting shoulder dystocia among women planned for vaginal delivery.
| Accelerated EFW growth velocity | Accelerated AC growth velocity | 36-week ultrasound EFW >95th centile | |
|---|---|---|---|
| Number (%) | 16 (5.0%) | 42 (13.2%) | 36 (11.3%) |
| Sensitivity | 28.6% (3.7% - 71.0%) | 42.9% (9.9% - 81.6%) | 14.3% (0.4% - 57.9%) |
| Specificity | 95.5% (92.6% - 97.5%) | 87.5% (83.3% - 90.9%) | 88.8% (84.7% - 92.0%) |
| Positive likelihood ratio | 6.4 (1.8–22.8) | 3.4 (1.4–8.4) | 1.3 (0.2–8.0) |
| Negative likelihood ratio | 0.8 (0.5–1.2) | 0.7 (0.3–1.2) | 1.0 (0.7–1.3) |
| Positive predictive value | 12.5% (3.8% - 33.9%) | 7.1% (3.0% - 16.0%) | 2.8% (0.5% - 15.3%) |
| Negative predictive value | 98.3% (97.4% - 99.0%) | 98.6% (97.3% - 99.2%) | 97.9% (97.1% - 98.4%) |
There were 318 women planned for vaginal birth in total. Ranges within brackets represent 95% confidence intervals. EFW = estimated fetal weight, AC = abdominal circumference.