Risk Score = 0.82 + [1.79 x a] + [61.21 x b] - [12.45 x b^{2}] - [6.48 x b^{3}] - [57.98 x c] + [9.42 x c^{2}] + [12.68 x c^{3}] - [6.01 x d] - [3.41 x d^{2}] + [4.52 x d^{3}] - [13.97 x e] + [7.79 x e^{2}] + [23.57 x f] + [4.97 x f^{2}] – [8.43 x g] – [4.35 x g^{2}]; probability of vaginal delivery = 1/(1 + e^{-Risk Score})

Model Performance

Hosmer-Lemeshow goodness-of-fit
χ2 = 5.02, 8 degrees of freedom, p = 0.76
Area under receiver operating characteristic curve
0.81 [95% CI 0.78–0.83]