Bishop score calculator
Scores a cervix on the five parameters Edward Bishop published in 1964 — dilation, effacement, station, consistency and position — for a total out of 13. It then reads that total three ways: the traditional favourable threshold above 8, the shortened three-item version, and the NICE cut-off of 6 that decides which induction method is offered.
Bishop score calculator
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How thin the cervix has become, as a percentage of its usual length. 0% is full length; 100% is paper thin.
Where the head sits relative to the bony ischial spines. The Bishop score uses the -3 to +3 scale, not the -5 to +5 scale ACOG later defined.
How the cervix feels. This and position are the two most subjective items on the score.
Which way the cervix points. It swings forward as labour approaches.
Parity changes the ripening target, and the original score was validated in women who had given birth before.
Choose a band for each of the five parts of the examination. All five come from one vaginal examination, so they are usually recorded together.
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How this is calculated
FormulaThe scoring table, in full
Five things are assessed at one vaginal examination. Dilation, effacement and station each score 0 to 3; consistency and position each score 0 to 2. The maximum is 13 and the minimum is 0.
Dilation, in centimetres
Closed scores 0. One to two centimetres scores 1. Three to four scores 2. Five centimetres or more scores 3.
Effacement, as a percentage
Nought to 30 per cent scores 0. Thirty-one to 50 per cent scores 1. Fifty-one to 80 per cent scores 2. More than 80 per cent scores 3. Effacement is how thin the cervix has become as a proportion of its usual length: 0 per cent is full length, 100 per cent is under a centimetre.
Station of the presenting part
Minus 3 scores 0. Minus 2 scores 1. Minus 1 or 0 scores 2. Plus 1 or plus 2 scores 3. Station is measured against the bony ischial spines. Bishop divided the distance above and below them into thirds, giving the minus 3 to plus 3 scale. ACOG later redefined station from minus 5 to plus 5 in centimetres; the Bishop score uses the older thirds-based scale.
Consistency
Firm scores 0, medium scores 1, soft scores 2. The usual teaching comparison is that a firm cervix feels like the tip of your nose and a soft one like your lower lip.
Position
Posterior scores 0, mid scores 1, anterior scores 2. The cervix points backwards for most of pregnancy and swings forward as labour approaches.
How the total is read
Above 8 is favourable. This is the traditional threshold, and it means an induced labour is expected to behave much like a spontaneous one. Note that it is above 8, so a score of exactly 8 does not meet it.
Six or less, versus more than 6, decides the method in the UK. NICE guideline NG207 does not use the word favourable at all. At a Bishop score of 6 or less it recommends dinoprostone as a vaginal tablet, gel or controlled-release pessary, or low-dose 25 microgram oral misoprostol, and says to consider a mechanical method such as a balloon catheter or an osmotic dilator where a drug is not suitable or the woman prefers one. Above 6 it recommends amniotomy with an intravenous oxytocin infusion.
Above 5 on the shortened version. Many clinicians score only dilation, effacement and station, out of 9. On that version the favourable threshold is above 5.
Six or eight as a ripening target. The California Maternal Quality Care Collaborative suggests continuing cervical ripening until the score reaches 6 for a woman who has given birth before, or 8 for a first baby. That is why this calculator asks about parity.
The modified score, which tops out at 12
A modified version replaces effacement with measured cervical length and scores dilation differently: 0 centimetres scores 0, one to two scores 2, three to four scores 4, and more than four scores 6. Cervical length above 2.5 centimetres scores 0, above 1.5 to 2.5 scores 1, above 0.5 to 1.5 scores 2, and 0.5 or less scores 3. Its maximum is 12 and its favourable threshold is 5 or more. If a number you have been given does not match this calculator, check which version produced it before assuming either is wrong.
What the score cannot do
It does not predict whether an induction will succeed. It is a subjective bedside assessment, two clinicians can score the same cervix differently, and some studies suggest it is less predictive of induction failure with newer ripening methods than it was with older ones. It also does not replace assessment by a midwife or obstetrician.
What a Bishop score actually is
If you have been offered an induction, someone has probably said a number at you. Six. Four. Nine. It was said quickly, in a room where several other things were happening, and it arrived attached to a decision you had not finished thinking about. The number is a Bishop score, and understanding it takes about four minutes.
It is a description of your cervix at one moment. Edward Bishop published it in 1964 as a way of making a subjective examination systematic: instead of a doctor saying the cervix felt promising, five specific things would be scored, added up, and written down. Sixty years later it is still the standard way to describe a cervix before an induction, and it is still the number your care hangs off.
Why five things and not one
Dilation is the one everybody has heard of, and on its own it is misleading. A cervix at two centimetres that is thick, firm, pointing backwards and with the baby's head still high is a different proposition from a cervix at two centimetres that is soft, thinned, anterior and with the head engaged. Both are two centimetres. Only one of them is close to labour.
The other four parameters capture that difference. Effacement measures thinning, which happens as collagen in the cervix breaks down and the tissue takes on water. Consistency measures the same process by feel. Position measures the way the whole cervix swings forward as the lower segment of the uterus draws up. Station measures how far the baby's head has descended into the pelvis, against the ischial spines, which sit halfway between the pelvic inlet and outlet.
None of these is a thing you did or failed to do. Cervical remodelling begins well before labour and runs at its own pace. A low score is not a sign that you have not walked enough, eaten enough pineapple or bounced enough on a ball.
The number that changes what happens next
In UK practice, the threshold that matters most is not 8. It is 6.
NICE guideline NG207 splits induction methods at a Bishop score of 6. At 6 or less, the cervix needs ripening first, so induction is offered with dinoprostone or low-dose oral misoprostol, or with a mechanical method such as a balloon catheter. Above 6, the cervix is considered ready enough to go straight to breaking the waters and starting an oxytocin drip.
This is why a score of 3 usually means a longer induction. Not because anything is wrong, but because there is a ripening stage before the labour stage, and ripening takes hours rather than minutes. Knowing that in advance changes what you pack and what you expect, which is most of what makes an induction bearable.
Favourable, unfavourable, and the word nobody defines
Outside the UK you will meet the word favourable. Most studies have used a score above 8 to mean a favourable cervix, and the useful thing about that threshold is what it implies: with a favourable cervix, the chance that an induction ends in a vaginal birth is about the same as it would be in spontaneous labour.
StatPearls is careful to note that the precise criteria defining favourable and unfavourable have never actually been established, and that the above-8 figure comes from studies mostly done in women at term who had given birth before, with uncomplicated pregnancies. If this is your first baby, you are outside the population the threshold was validated in. That is not a reason to ignore the number; it is a reason not to read too much into a single point either side of it.
What a low score does not mean
It does not mean your induction will fail. It does not mean you will need a caesarean. It does not mean your body is not working. A cervix scoring 3 today is very often a cervix scoring 9 after a night with a pessary in, because that is precisely what ripening agents do.
It is also worth knowing that the Bishop score is subjective. It depends on one clinician's fingers and one clinician's judgement, particularly for consistency and position, which are the two softest items on the list. Scores recorded by different people a few hours apart can differ without either being wrong. Some units now measure cervical length by transvaginal ultrasound instead, and the research comparing the two is genuinely mixed.
What is physically happening in a cervix
Outside pregnancy the cervix is mostly tightly packed collagen, and its job is to stay shut. Across pregnancy the density of that collagen falls while hyaluronic acid and water content rise. As birth approaches, inflammatory mediators drive prostaglandin production, collagen breaks down, and the tissue softens and becomes more vascular. That is the process every one of the five Bishop parameters is measuring from a different angle, and it starts well before labour does.
It is also why ripening agents work. Dinoprostone is a prostaglandin. A balloon catheter works mechanically and by triggering local prostaglandin release. Neither is starting labour; both are finishing a job the body had already begun, which is a more accurate way to think about a low score than treating it as a failure to launch.
Questions worth asking
What is my Bishop score, and which version did you use? Does that mean starting with a ripening agent or going straight to breaking my waters? How long is the ripening stage likely to take here? Will you rescore me before the next step, and when?
NICE recommends offering to reassess wellbeing and the Bishop score at appropriate intervals during an induction, so asking when the next assessment is due is a normal question with a real answer.
When this tool is not the right one
Digital cervical examination is avoided in some situations, including placenta praevia and preterm prelabour rupture of membranes, so there will be no Bishop score to enter. And if you are already in labour, contractions rather than a cervical score are the useful thing to be tracking. This calculator reads a published table. It does not know your pregnancy, and it does not replace assessment by the people looking after you.
Sources
- Bishop Score — StatPearls, NCBI Bookshelf, accessed
- Effect of cervical Bishop score on induction of labor at term in primiparas using Foley catheter balloon — BMC Pregnancy and Childbirth (PMC), accessed
- Inducing labour (NG207) — NICE, accessed
- Inducing labour (NG207): Recommendations — NICE, accessed
- Methods for the induction of labour (NG207 evidence review) — NICE, via NCBI Bookshelf, accessed