Table 3 Predicted and observed probabilities of successful vaginal birth among the antenatal 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 | 0 | 0 | 0 | NA |
31–40 | 6 | 3 | 50.0 | 41.80- 67.10 |
41–50 | 8 | 5 | 62.5 | 59.12- 92.26 |
51–60 | 52 | 36 | 69.2 | 63.60- 79.01 |
61–70 | 124 | 96 | 77.4 | 70.20 – 82.67 |
71–80 | 116 | 96 | 82.8 | 69.35 – 89.91 |
81–90 | 186 | 162 | 87.1 | - 68.1 – 110.7 |
91–100 | 222 | 201 | 90.5 | -67.94- 97.05 |