Synopsis
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.
- Obtain the gestation and circumstances of previous spontaneous birth or pregnancy loss rather than treating every preterm delivery as the same risk.
- For singleton pregnancy, use trained transvaginal cervical-length assessment between 16+0 and 24+0 weeks when risk warrants screening.
- A cervical length of 25 mm or less is the prevention threshold; it is not the same as the symptomatic later-pregnancy 15-mm threshold.
- Offer a choice of vaginal progesterone or prophylactic cerclage when both a qualifying history and a cervix of 25 mm or less are present.
- Consider vaginal progesterone when either qualifying history or short cervix alone is present, starting between 16+0 and 24+0 weeks and continuing to at least 34 weeks.
- Consider cerclage with short cervix and previous PPROM or cervical trauma, and document removal arrangements at insertion.
- Twin and triplet care follows NICE NG137: offer cervical-length assessment at 16–20 weeks and vaginal progesterone 200 mg nightly for a cervix of 25 mm or less.
Key red flags
Painful regular contractions with a cervical stitch in place requires urgent assessment and consideration of removal to prevent cervical injury.
Infection, active vaginal bleeding or uterine contractions contraindicate emergency cerclage under the NICE pathway.
Investigation priorities
Distinguish spontaneous early birth, PPROM, cervical change and medically indicated delivery.
Management branches
A booking history identifies previous spontaneous early birth, mid-trimester loss or cervical risk.
- Document the mechanism and gestation of each relevant pregnancy and details of cervical or uterine procedures, then arrange early preterm-prevention review.
- Plan trained transvaginal cervical surveillance within the 16+0–24+0-week singleton window, tailored to the specialist risk assessment.
- Give practical advice about smoking cessation, infection symptoms and urgent maternity contact without implying that prevention guarantees term birth.
Key medicines
Vaginal micronised progesterone in high-risk singleton pregnancyOne licensed preparation, Utrogestan Vaginal 200 mg, is inserted vaginally once nightly from around 20 weeks until 34 weeks; NICE allows initiation between 16+0 and 24+0 weeks with continuation until at least 34 weeks, so check the exact product and any off-label timing.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.
Progesterone for short cervix in twin or triplet pregnancyUnder NICE NG137, offer progesterone 200 mg vaginal capsules at bedtime once daily for cervical length of 25 mm or less, continuing until 34 weeks or birth if earlier.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.