Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Identify pregnancies that benefit from cervical surveillance, select progesterone or cerclage according to history and scan findings, and maintain a clear plan for symptoms and suture removal.
Spontaneous preterm birth is a syndrome with several pathways, including premature cervical change, membrane rupture and inflammation. Prevention starts by understanding the earlier pregnancy. A birth induced for severe pre-eclampsia is different from spontaneous labour at the same gestation; a painless mid-trimester loss differs from an acute febrile presentation. Record previous gestations, membrane events, cervical procedures, uterine anomalies and the neonatal outcome, then arrange timely specialist review. Early referral matters because the useful window for cervical surveillance and prophylactic intervention ends long before many patients develop symptoms.
Cervical length is measured transvaginally by a trained operator using a reproducible technique. Avoid excessive probe pressure or bladder distortion that can falsely lengthen the cervix. The 16+0–24+0-week measurement addresses the probability of subsequent early birth in an otherwise preventive setting. NICE uses 25 mm or less as the short-cervix threshold. The result should be interpreted with history and gestation, rather than used as a stand-alone prediction of inevitable delivery. A normal measurement does not erase previous risk or remove the need for symptom advice.
Previous spontaneous birth up to 34+0 weeks or loss from 16+0 weeks identifies a history that can change preventive treatment choices.
Prior cervical excision or other injury needs details of the procedure and obstetric history to determine referral and surveillance rather than automatic intervention.
A correctly measured cervix of 25 mm or less in the mid-trimester is an actionable risk finding even when no contractions are reported.
Painless dilatation with exposed intact membranes needs urgent specialist evaluation before deciding whether emergency cerclage is appropriate.
Do not substitute oral capsules or early-miscarriage doses without checking formulation. For Utrogestan Vaginal 200 mg, exclude PPROM before treatment and discontinue if membranes rupture. Check unexplained bleeding, thromboembolic or liver disease, and peanut or soya allergy against the product contraindications.
Use in twin or triplet pregnancy may be off label for the selected product; do not extend this recommendation to routine treatment of every multiple pregnancy with a normal cervix.
Hypertensive or growth-related early delivery may warrant placental-risk prevention, but does not automatically satisfy the spontaneous-preterm-birth criteria for cervical intervention.
NICE removed the old single-product licensing note in February 2026; prescribers still need to check the selected formulation, population and start time.
The updated twin and triplet recommendation supports progesterone for a short cervix, so older advice that progesterone never helps multiples is outdated.
Leaving a transvaginal stitch in during established labour can injure the cervix, making contingency documentation a clinical safety requirement.
Applying singleton prevention criteria to twins without checking the specific NICE multiple-pregnancy recommendation.
Describing all vaginal progesterone for preterm prevention as unlicensed despite currently licensed products.
Placing emergency cerclage in the presence of infection, active bleeding or uterine contractions.
Failing to document when and how the cervical stitch will be removed before labour or during an unexpected preterm presentation.
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A singleton pregnancy is at 20 weeks. The patient previously had spontaneous labour and birth at 30 weeks, and transvaginal ultrasound now shows a cervical length of 22 mm. What should be offered?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 7 Sept 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
Progesterone regimens and licences depend on product, formulation and indication. NICE advises starting preventive vaginal progesterone between 16+0 and 24+0 weeks and continuing until at least 34 weeks. A licensed example is Utrogestan Vaginal 200 mg nightly from around 20 to 34 weeks for a qualifying high-risk singleton pregnancy. Starting earlier or using another product requires checking that product's licence and documenting any off-label use; the February 2026 NICE update acknowledges that more than one product is now licensed. This is distinct from progesterone given for early-pregnancy bleeding, which has a different regimen and evidence base.
Emergency cerclage is a separate rescue decision for a dilated cervix with exposed but unruptured membranes between 16+0 and 27+6 weeks. Exclude infection, active bleeding and contractions before considering it, and involve consultant obstetric and neonatal clinicians. A stitch cannot reliably reverse an established infective or labour process. Every insertion requires a removal plan, including what happens with labour or PPROM. A transvaginal stitch is generally removed before labour at 36+1–37+0 weeks, with individual arrangements for planned caesarean birth; a transabdominal stitch requires a different birth and removal strategy.