vbac_success_predictor: Vaginal Birth After Cesarean (VBAC) Success Predictor (MFMU...

In cliot: Clinical Indices and Outcomes Tools

Vaginal Birth After Cesarean (VBAC) Success Predictor (MFMU 2021 Model)

Description

Calculates the predicted probability of a successful vaginal birth after cesarean (VBAC) for women with one prior low-transverse cesarean section. This function uses the updated 2021 MFMU Network model which excludes race and ethnicity variables, incorporating age, BMI, prior vaginal delivery history, recurring indication for prior cesarean, and history of chronic hypertension.

Usage

vbac_success_predictor(age, height_in, weight_lb, previous_vaginal_delivery,
                       previous_vbac, recurring_indication_cesarean,
                       treated_chronic_hypertension)

Arguments

age	Numeric. Maternal age in years.
height_in	Numeric. Maternal height in inches.
weight_lb	Numeric. Pre-pregnancy weight in pounds.
previous_vaginal_delivery	Numeric (0 or 1). Has the patient had any prior vaginal delivery (either before or after the cesarean)? (1 = Yes).
previous_vbac	Numeric (0 or 1). Has the patient had a successful VBAC previously? (1 = Yes).
recurring_indication_cesarean	Numeric (0 or 1). Was the indication for the prior cesarean section a recurring cause (e.g., arrest of dilation or descent)? (1 = Yes).
treated_chronic_hypertension	Numeric (0 or 1). Is the patient being treated for chronic hypertension? (1 = Yes).

Details

The probability (P) is calculated using the logistic regression equation from the 2021 validation study:

P = \frac{1}{1 + e^{-x}}

Where x = 3.302 - 0.043(Age) - 0.052(BMI) + 0.832(AnyVaginal) + 0.489(PriorVBAC) - 0.622(RecurringIndication) - 0.513(Hypertension).

Value

A list containing:

Predicted_VBAC_Success

The estimated percentage chance of a successful vaginal delivery.

References

Grobman WA, et al. Prediction of Vaginal Birth After Cesarean Delivery in Term Gestations: A Calculator Without Race and Ethnicity. Am J Obstet Gynecol. 2021;225(6):664.e1-664.e7. doi:10.1016/j.ajog.2021.05.021

Examples

# Example 1: High Probability
# 30yo, BMI ~24, Prior VBAC, Non-recurring indication
vbac_success_predictor(30, 65, 145, 1, 1, 0, 0)

# Example 2: Lower Probability
# 35yo, BMI ~35, No prior vaginal, Recurring indication (arrest), Hypertension
vbac_success_predictor(35, 64, 205, 0, 0, 1, 1)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.