The Bishop Score Calculator estimates how ready (or “ripe”) a woman’s cervix is for labour induction. Introduced by Edward Bishop in 1964, it combines five findings from a vaginal examination into a single number that predicts whether inducing labour is likely to lead to a successful vaginal delivery.
How it works
Five cervical and fetal parameters are each scored and summed. Three parameters score 0–3 and two score 0–2, for a maximum total of 13:
- Dilation — 0 (closed) = 0, 1–2 cm = 1, 3–4 cm = 2, 5+ cm = 3.
- Effacement — 0–30% = 0, 40–50% = 1, 60–70% = 2, 80%+ = 3.
- Station (relative to ischial spines) — −3 = 0, −2 = 1, −1/0 = 2, +1/+2 = 3.
- Consistency — firm = 0, medium = 1, soft = 2.
- Position — posterior = 0, mid = 1, anterior = 2.
The total maps to an interpretation: ≥8 favourable (induction likely to succeed), 6–7 intermediate, and ≤5 unfavourable (cervical ripening is usually recommended first).
Example and notes
A cervix that is 3 cm dilated (2), 70% effaced (2), at station −1 (2), soft (2),
and anterior (2) scores 2 + 2 + 2 + 2 + 2 = 10, which is favourable. A closed,
firm, posterior cervix at station −3 scores near 0 and signals the need for
ripening.
The Bishop score guides but does not dictate management. A higher score correlates with a shorter induction and a lower caesarean risk, but clinical context — gestational age, indication for induction, and maternal preference — always informs the final decision.
Interpreting the score in practice
| Score | Interpretation | Typical clinical approach |
|---|---|---|
| 0 – 5 | Unfavourable cervix | Cervical ripening before induction |
| 6 – 7 | Intermediate | Clinical judgement; ripening often beneficial |
| 8 – 13 | Favourable cervix | Induction likely to succeed; proceed with oxytocin or amniotomy |
The score is most useful as a decision-support tool at the start of an induction pathway. A score of 8 or above at assessment suggests the cervix is ripe enough that oxytocin augmentation or artificial rupture of membranes is likely to establish active labour without prior pharmacological ripening. A score of 5 or below generally prompts a ripening step first — prostaglandins (dinoprostone gel or a slow-release pessary) or a mechanical method such as a balloon catheter — to bring the cervix to a more favourable state before induction proper.
Factors that influence the score and how it changes
The score is not static. After a course of prostaglandins, reassessment typically shows improvement in consistency, position, and effacement — often before significant dilation occurs. Serial assessment every 6 to 8 hours during ripening is common practice. Fetal descent (station) also progresses as engagement increases, particularly in nulliparous women approaching term.
Parity affects the practical significance of individual parameter values. Nulliparous women often start with a lower score than multiparous women at the same gestational age, and clinicians may weight the same score differently depending on parity, gestational age, and the indication for induction.
Limitations and alternatives
The Bishop score was developed on a relatively small cohort in 1964 and was not designed for the range of induction settings used today. The modified Bishop score adjusts the point values of some parameters. Research has also evaluated ultrasonographic cervical length measurement (transvaginal ultrasound, typically of the cervix at 25–35 mm or shorter as a threshold) as a predictor of induction success. In many centres the two approaches are used together, with the sonographic measurement providing an objective length assessment alongside the clinical Bishop score. This calculator follows the original Bishop scoring, which remains the most widely recognised.