Table 4.

Multivariable predictors of TOLAC

Predictors included in multivariable model1	Type 3 p-value	Adjusted Odds Ratio (95% CI)
Model 1
Recruitment site	0.21
Northwestern		Reference
San Francisco Bay Area		2.02 (0.92–4.45)
Massachusetts General		1.66 (0.79–3.46)
VBAC calculator risk score 2	0.011	1.36 (1.07–1.73)
Strength of preference for vaginal delivery score 3	< 0.001	1.29 (1.18–1.40)
Time trade off utility for ERCD, minor surgical complications 3	0.026	0.79 (0.64–0.97)
Model 2
Recruitment site	0.63
Northwestern		Reference
San Francisco Bay Area		1.38 (0.54–3.53)
Massachusetts General		1.47 (0.68–3.18)
VBAC calculator risk score	0.0097	1.48 (1.10–1.98)
Strength of preference for vaginal delivery score	0.0025	1.17 (1.06–1.30)
Value of the experience of labor and vaginal birth	< 0.001	3.46 (2.01–5.96)
Opinion of important other regarding TOLAC	0.021	1.47 (1.06–2.04)

¹Candidate predictors evaluated included recruitment site, VBAC calculator risk score, TTO utilities, strength of preference for vaginal delivery, attitudes and social norms around delivery mode, and plans for future childbearing. Recruitment site and probability of VBAC were included in all models a priori. All other predictors were evaluated using forward selection with model entry set at p<0.05. Initial model evaluated utilities and strength of preference for vaginal delivery (presented in the top portion of the table). Model 2 (presented in the bottom portion of the table) evaluated utilities, attitudes, social normal and plans for future child bearing. Predictors with p < 0.05 are bolded.

²Utilizing the NICHD pre-admission VBAC calculator. aOR is for every 10-point increase in the likelihood of VBAC if a TOLAC is undertaken.

³aOR for every 0.1 point increase on a 0–1 scale