Calculator: Trial of labor after cesarean (TOLAC) for use at entry to prenatal care

Input

Maternal age
Height
Pre-pregnancy weight
Obstetric history	No previous vaginal deliveries (0)
	Previous vaginal delivery before prior cesarean (0.868)
	Previous VBAC (1.869)
Arrest disorder at previous cesarean	No (0)
	Yes (0.597)
On antihypertensive drug therapy	No (0)
	Yes (0.966)

Results

Important: Inputs must be complete to perform calculation.


Probability of successful vaginal delivery		%

Notes

Due to limited precision in publically available data, there may be small (≤1%) differences between results in this calculator and the results in the online TOLAC calculator provided by the Maternal-Fetal Medicines Units (MFMU).

Equations used

Terms = (0.056 * Height) + Obstetric history - Arrest disorder at previous cesarean - (0.023 * Maternal age) - (0.024 * Pre-pregnancy weight) - On antihypertensive drug therapy - 5.952

Probability of successful vaginal delivery = 100 * e^(Terms) / (1 + e^(Terms))

Equation parameters, such as Obstetric history, have 2 or more discrete values that may be used in the calculation. The numbers in the parentheses, eg, (0), represent the values that will be used.

References

Grobman WA, Sandoval G, Rice MM, et al. Prediction of vaginal birth after cesarean delivery in term gestations: a calculator without race and ethnicity. Am J Obstet Gynecol 2021; 24:S0002.

Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

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Calculator: Trial of labor after cesarean (TOLAC) for use at entry to prenatal care