Suspected preterm labour (under 37 weeks)
Regular contractions before 37+0 weeks with intact membranes. Ruptured membranes: use the PPROM pathway.
All Pathways
Obstetrics & GynecologyManagement
Preterm Labor Management (ACOG 2016)
Preterm Labor Management (ACOG 2016): Suspected preterm labour (under 37 weeks) → Red flags before examination → Initial assessment → Preterm labour con...
Pathway Overview
19 steps
Algorithm Steps
19 total
01Start 02Warning Red flags before examination
Unstable mother, severe pre-eclampsia or fetal distress: call the obstetric consultant now.
- Vaginal bleeding: exclude placenta praevia by ultrasound before any digital exam; consider abruption
- Fever, uterine tenderness, maternal or fetal tachycardia: suspect chorioamnionitis; no tocolysis; consultant review, IV antibiotics, plan birth
- Ruptured membranes: use the PPROM pathway
03Action Initial assessment
Confirm gestation and assess mother and fetus. Speculum before any digital exam.
- Confirm gestational age from the earliest ultrasound
- Maternal vital signs, abdominal palpation, fetal heart rate or CTG
- Sterile speculum first: fluid, bleeding, dilation; GBS swab; fFN swab before any digital exam or TVUS
- Digital cervical exam only after praevia and ruptured membranes are excluded
- fFN valid only with intact membranes, cervix under 3 cm and no heavy bleeding
- Transvaginal cervical length (CL) if available; midstream urine for culture
04Decision Preterm labour confirmed?
Regular contractions with cervical change, or cervix 2 cm or more dilated.
- If Yes
05Decision Gestational age?
Choose the next step for the current gestation.
- 24+0 to 33+6 wks
06Action 24+0 to 33+6 weeks: preterm
Give steroids. Consider tocolysis. Magnesium sulfate if birth is expected and under 30 weeks (AU) or 32 weeks (US).
- Antenatal corticosteroids (next steps)
- Tocolysis up to 48 h to complete steroids or transfer, if no contraindication
- Neonatal counselling; transfer in utero to a centre with the right NICU level
- Rural or remote site: call the retrieval service early
- GBS: intrapartum prophylaxis if GBS positive or unknown
07Warning Before steroids: diabetes and infection
Do not delay an urgent birth to complete steroids.
- Pre-existing diabetes: close BGL monitoring and diabetes team; steroids cause hyperglycaemia and can cause DKA
- Systemic infection (sepsis, active TB): consultant decision before steroids
- Give steroids even if birth is likely within 24 h
08Action Antenatal corticosteroids
One course. Greatest benefit if birth is 24 h to 7 days after the second dose.
- AU: betamethasone (Celestone Chronodose) 11.4 mg IM, 2 doses 24 h apart
- US: betamethasone 12 mg IM, 2 doses 24 h apart
- Or dexamethasone 6 mg IM every 12 h, 4 doses
- Repeat, AU (ANZ): consultant decision; 32+6 weeks or less, birth expected within 7 days, 7 days or more after the course: single 11.4 mg IM dose (up to 3, each 7 days or more apart)
- Repeat, US (ACOG): consultant decision; under 34 weeks, birth expected within 7 days: one repeat course if the last course was over 14 days ago (from 7 days if needed)
- Diabetes: check BGL during and after the course
09Warning No tocolysis if any of these
Tocolysis only from 22+0 to 33+6 weeks and only for up to 48 h.
- Abruption, bleeding with an unstable mother, severe pre-eclampsia or eclampsia
- Chorioamnionitis, non-reassuring fetal status, fetal death or lethal anomaly
- Drug-specific: nifedipine - hypotension or heart disease; indomethacin - 32 weeks or more, renal or liver disease, peptic ulcer, bleeding disorder, NSAID-sensitive asthma, oligohydramnios
10Action Tocolysis: up to 48 h (under 34 weeks)
Only to gain time for steroids, magnesium or transfer. No maintenance tocolysis.
- First line: nifedipine immediate-release 20 mg PO; repeat 20 mg after 30 min if contractions persist
- Then nifedipine 20 mg PO every 3 to 8 h; maximum 160 mg/day
- Check BP and pulse every 30 min; treat hypotension with IV fluid; continuous CTG
- Nifedipine: do not combine with salbutamol or terbutaline; caution with magnesium sulfate (hypotension)
- Second line, under 32 weeks only: indomethacin 100 mg PR, then 25 mg PO every 4 h; stop by 48 h
- Beta-agonists: last line; not with heart disease, diabetes or thyroid disease
11Decision Birth expected within 24 h?
Labour progresses, or birth is planned.
- If Yes
12Warning Under 30 weeks (AU) or 32 weeks (US): check before magnesium sulfate
Do not delay an urgent birth to give magnesium sulfate. Already on magnesium sulfate for pre-eclampsia: continue it; no second loading dose.
- Myasthenia gravis: do not give magnesium sulfate
- Renal impairment or urine output under 25 mL/h: toxicity risk; senior review before and during infusion
- Nifedipine increases magnesium effects: watch for hypotension
13Action Under 30 weeks (AU) or 32 weeks (US): magnesium sulfate for neuroprotection
Give when birth is expected within 24 h. Reduces cerebral palsy. Older gestation: go to the next step.
- Load: 4 g IV over 20 to 30 min (8 g/100 mL premixed bag: 50 mL)
- Then 1 g/h IV; stop at birth or at the local time limit (4 h to 24 h)
- Check reflexes, respiratory rate and BP every 15 min for 2 h, then hourly; urine output hourly
- Stop and call a doctor if reflexes are absent, respiratory rate under 12/min or urine under 25 mL/h
- Toxicity: calcium gluconate 10% 10 mL (1 g) IV over 3 to 10 min, with ECG monitoring
14Outcome Birth expected: prepare for preterm birth
Neonatal team at the birth. GBS prophylaxis if positive or unknown.
- Neonatal team present; transfer in utero only if birth is not imminent
- Intrapartum GBS prophylaxis if GBS positive or unknown
- Delay cord clamping if the baby does not need resuscitation
- Record the times of steroid and magnesium doses
- Caesarean section for usual obstetric indications only
If No15Outcome Contractions settle: birth not expected within 24 h
If steroids were started, complete the course. If on tocolysis, stop by 48 h. Senior review before discharge.
- If steroids were started: complete the course
- If on tocolysis: stop by 48 h; no maintenance tocolysis
- Senior obstetric review before discharge
- Return at once if contractions, bleeding, fluid loss or reduced fetal movements
- Plan follow-up and place of birth
- 34+0 to 36+6 wks
16Action 34+0 to 36+6 weeks: late preterm
No tocolysis. Steroids only per local policy; not in pre-existing (type 1 or 2) diabetes.
- Tocolysis is not recommended
- US (ACOG): one betamethasone course may be considered if birth likely within 7 days, no previous course and no chorioamnionitis
- Do not delay an indicated birth (such as severe pre-eclampsia) to give steroids
- AU (ANZ 2015): steroids up to 34+6 weeks; after that, follow local policy
- If steroids given: monitor the newborn for hypoglycaemia
- GBS: intrapartum prophylaxis if GBS positive or unknown
- Inform the neonatal team; plan place of birth
- Path rejoins step 11Shared downstream outcome
- 22+0 to 23+6 wks
17Action 22+0 to 23+6 weeks: periviable
Active care or comfort care is a shared decision with the family.
- Urgent obstetric and neonatal consultant counselling
- If active care is planned: steroids may be considered from 22+0 weeks
- If active care is planned: magnesium sulfate for neuroprotection
- Tocolysis has no proven neonatal benefit; use only to gain time for steroids or transfer
- Transfer in utero to a tertiary perinatal centre if time allows
- If comfort care is chosen: no steroids, magnesium or tocolysis; palliative care
- Path rejoins step 07Shared downstream outcome
- Under 22+0 wks
18Outcome Under 22+0 weeks: previable
Supportive care. Steroids, magnesium sulfate and tocolysis are not recommended.
- Senior obstetric and neonatal counselling on prognosis
- No antenatal corticosteroids before 22+0 weeks
- No tocolysis or magnesium sulfate for neuroprotection
- Treat maternal causes such as infection or bleeding
- Offer palliative and bereavement support
If No19Outcome Not in preterm labour
No cervical change and contractions settle. Positive fFN or short cervix: senior review before discharge.
- Negative fFN or CL 30 mm or more: low risk of birth in the next 7 days
- Positive fFN or short CL: senior review; consider admission and steroids
- Senior obstetric review before discharge; treat any cause such as UTI
- Return at once if contractions, bleeding, fluid loss or reduced fetal movements
Guideline Source
ACOG Practice Bulletin No. 171: Management of Preterm Labor (2016, reaffirmed 2022)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Doses follow Australian (KEMH WA, ANZ) regimens; US units may use other ACOG-accepted regimens. Check the local protocol.
- Intact membranes only; for PPROM use the PPROM pathway. Periviable care (22+0 to 23+6 weeks) needs individual senior decisions.
- Tocolysis gives up to 48 h of delay; it does not improve neonatal outcome on its own.
- Cervical length and fFN cut-offs vary by institution.
Contraindicated Populations
Preterm prelabour rupture of membranes (use the PPROM pathway)Term pregnancy (37+0 weeks or more)
Applicable Regions
AUNZUSGlobal
AU: Betamethasone is Celestone Chronodose 11.4 mg IM. ANZ guidance: magnesium sulfate for neuroprotection under 30 weeks; antenatal steroids up to 34+6 weeks (ANZ 2015), some units to 35+6 weeks. Nifedipine immediate-release 10 mg tablets are supplied under SAS Category A; do not crush modified-release tablets.
US: ACOG: magnesium sulfate for neuroprotection under 32 weeks; betamethasone 12 mg IM; late preterm steroids (34+0 to 36+6 weeks) may be considered if no prior course and no pre-existing diabetes.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Preterm Labor Management (ACOG 2016)?
The Preterm Labor Management (ACOG 2016) is a management clinical algorithm for Obstetrics & Gynecology. It provides a structured decision tree to guide clinical decision-making, based on ACOG Practice Bulletin No. 171: Management of Preterm Labor (2016, reaffirmed 2022).
What guideline is the Preterm Labor Management (ACOG 2016) based on?
This algorithm is based on ACOG Practice Bulletin No. 171: Management of Preterm Labor (2016, reaffirmed 2022) (DOI: 10.1097/AOG.0000000000001711).
What are the limitations of the Preterm Labor Management (ACOG 2016)?
Known limitations include: Doses follow Australian (KEMH WA, ANZ) regimens; US units may use other ACOG-accepted regimens. Check the local protocol.; Intact membranes only; for PPROM use the PPROM pathway. Periviable care (22+0 to 23+6 weeks) needs individual senior decisions.; Tocolysis gives up to 48 h of delay; it does not improve neonatal outcome on its own.; Cervical length and fFN cut-offs vary by institution.. Individual patient factors may require deviation from these recommendations.
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