Table 4 Predicted and observed probabilities of successful vaginal birth among the intrapartum group, according to Grobman model
Predicted probability VBAC (%) | Number of pregnant women (n) | Attended VB | Observed Probability | Confidence Interval 95% (Lower – Upper) |
|---|---|---|---|---|
0–10 | 0 | 0 | 0 | NA |
11–20 | 0 | 0 | 0 | NA |
21–30 | 1 | 1 | 100.0% | NA |
31–40 | 8 | 6 | 75.0% | - 50.31 – 87.74 |
41–50 | 13 | 10 | 76.9% | - 65.54- 91.27 |
51–60 | 56 | 38 | 67.9% | - 55.88 – 88.81 |
61–70 | 118 | 89 | 75.4% | 53.48 – 90.81 |
71–80 | 118 | 99 | 83.9% | 68.90 – 94.98 |
81–90 | 183 | 156 | 85.2% | 63.46 – 93.96 |
91–100 | 200 | 179 | 89.5% | 67.09 – 109.63 |