Flamm VBAC Score
Flamm VBAC admission score (0–10) from maternal age, prior-vaginal-birth history, the reason for the prior cesarean, cervical effacement, and dilation, mapping to a success probability.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Age under 40
- Yes
- Prior vaginal-birth history
- After the first cesarean only
- Cervical effacement at admission
- 25 to 75%
Result: Flamm VBAC admission score 5/10: estimated likelihood of a successful vaginal birth about 77%.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Score 0-2 / 3 / 4 / 5
- estimated VBAC success about 49% / 60% / 67% / 77%.
- Score 6 / 7 / 8-10
- about 89% / 93% / 95%. Free substitute for the paywalled Grobman MFMU model.
What you enter
- Age under 40 (+2)
- Prior vaginal-birth history: none, before the cesarean only, after only, or both before and after
- Prior cesarean for a reason other than failure to progress (+1)
- Cervical effacement at admission: lt25 is under 25 percent, mid is 25 to 75, gt75 is over 75
- Cervical dilation ≥ 4 cm (+1)
How this is calculated
- Factors
- age < 40 (2), prior vaginal birth (before & after 4, after 2, before 1, none 0), prior cesarean not for failure to progress (1), effacement (>75% 2, 25-75% 1, <25% 0), dilation >= 4 cm (1).
Flamm BL, Geiger AM. Vaginal birth after cesarean delivery: an admission scoring system. Obstet Gynecol. 1997;90(6):907-910. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.