The Bishop score grades how ready the cervix is for induction of labor using five findings from a routine cervical exam. Introduced by Edward Bishop in 1964, it remains the most widely used pre-induction scoring system and helps clinicians decide whether to proceed with induction directly or ripen the cervix first. This article explains how the score is built, how to read it, and where its limits lie.
How the Bishop score works
Five components are each graded by tier and summed. Cervical dilation, effacement, and fetal station each score 0 to 3 points; cervical consistency and position each score 0 to 2 points. That asymmetry is deliberate — it is what caps the total at 13 rather than 15.
Three of the components (dilation, effacement, station) are relatively objective measurements, while two (consistency and position) are clinical-feel judgments. The total maps to a favorability band: 0–5 unfavorable, 6–7 intermediate, and 8–13 favorable. The single most cited rule is that a score of 8 or higher indicates a favorable cervix.
Reading the score and favorability
A favorable Bishop score (commonly ≥ 8) means the cervix is ripe and the likelihood of a successful induction ending in a vaginal delivery approaches that of spontaneous labor. A low score signals an unfavorable, unripe cervix, where induction is more likely to be long or unsuccessful, so cervical ripening with prostaglandins or a mechanical balloon catheter is often used first.
The 6–7 range is genuinely indeterminate. Different institutions and the various modified Bishop scores draw the favorable line at 6, 7, or 8, so the number that triggers ripening at one hospital may differ at another. The score is one input into a broader decision that also weighs the indication for induction, the patient's parity, and fetal and maternal status.
Limits and how it should be used
The Bishop score is a prediction aid, not a guarantee. A favorable score does not ensure a vaginal delivery, and an unfavorable score does not preclude one. Its two clinical-feel components (consistency and position) introduce inter-observer variability, and several modified versions exist that adjust points for factors such as parity, pre-eclampsia, or post-dates pregnancy — so a score computed one way may not match another.
This calculator is for education and clinical reference only. Cervical examination and any decision about induction of labor must be made by the treating obstetric provider based on the complete clinical picture. It should never be the sole basis for a management decision.