Background Information
This topic is often confusing, as it involves the interplay of three key factors:
- Gestation (term vs preterm)
- Membrane status (ruptured vs intact)
- Labour status (in labour vs not in labour)
However, this becomes much clearer by first understanding the definitions, then navigating the clinical scenarios section.
Definition
Gestational age and definitions:
| Category | Definition |
|---|---|
| Preterm | <37 weeks of gestation |
| Term | 37-41 weeks of gestation |
| Post-term | ≥42 weeks of gestation |
PROM, P-PROM, preterm labour definitions:
| Term | Definition | Key points |
|---|---|---|
| Pre-labour rupture of membrane (PROM) (at term) | Rupture of membranes before onset of labour at ≥37 weeks (at term) | Occurs at term
Labour has NOT started yet |
| Pre-term, pre-labour rupture of membrane (P-PROM) | Rupture of membranes before onset of labour at <37 weeks (pre-term) | Occurs at pre-term
Labour has NOT started yet |
| Preterm labour |
Onset of labour at <37 weeks |
Labour is defined by regular uterine contractions with progressive cervical dilatation (from 4cm)
Rupture of membrane may be present or absent |
The majority of rupture of membranes occurs spontaneously at term (SROMSpontaneous rupture of membranes), typically just before or during the onset or progression of labour (this is physiological).
Only a minority of pregnancies at term develop PROM (8-10%). P-PROM is even rarer (2-3% of pregnancies).[Ref]
Clinical Scenarios
| Scenario | Definition / category |
|---|---|
| 36-week pregnant woman with regular contractions | Preterm labour |
| 35-week pregnant woman with rupture of membranes, no contractions | P-PROM |
| 39-week pregnant woman with rupture of membranes, no contractions | PROM (at term) |
| 39-week pregnant woman with regular contractions, membranes intact | Term labour |
| 35-week pregnant woman with contractions + rupture of membranes | Preterm labour (with ROM) |
| 38-week pregnant woman with contractions + rupture of membranes | Term labour (with ROM) |
Pre-Labour Rupture of Membrane (PROM) (At Term)
Assessment
Initial assessment: triage assessment over the phone with a midwife to exclude the following risk factors:
| Maternal factors |
|
| Fetal factors |
|
Subsequent action:
- If ANY of the above risk factors are present or if there is any uncertainty → advise the woman to attend the maternity unit immediately
- If there are NO risk factors:
- See the women within 12 hours, or
- ASAP if she has any concerns or wishes to be induced immediately
Management
Offer the women EITHER of the following:
- Expectant management for up to 24 hours, then offer induction (if labour has not started spontaneously), OR
- Immediate induction of labour
For more information on labour induction, see the Induction of Labour article.
IMPORTANT EXCEPTIONS:
If the woman is GBS +ve and has pre-labour rupture of membrane at term → immediate IAPIntrapartum antibiotic prophylaxis and induction of labour is necessary. See the Group B Streptococcus in Pregnancy article for more information.
If a woman presents with symptoms suggestive of intrauterine infection (e.g. fever, tachycardia, abnormal or offensive vaginal discharge, lower abdominal pain), expectant management is contraindicated.
Advise the woman that:
- There is a higher risk of serious neonatal infection in PROM
- 60% of women with PROM will go into labour within 24 hours
Pre-Term, Pre-Labour Rupture of Membrane (P-PROM)
Assessment
If P-PROM is suspected clinically (from maternal history):
| Step | Description | Subsequent action |
|---|---|---|
| 1 – Sterile speculum examination | Look for pooling of amniotic fluid in the posterior vaginal fornix | If pooling of fluid is observed → P-PROM is confirmed (no further tests are required)
If no amniotic fluid pooling is observed → step 2 |
| 2 – Vaginal fluid biochemical testing | Consider testing vaginal fluid for:
|
+ve Test (detection) is supportive of P-PROM |
Assessment / investigations that are NOT recommended:
- Nitrazine testing
Nitrazine paper detects alkaline pH.
Amniotic fluid is alkaline, whereas normal vaginal secretions are acidic.
is explicitly NOT recommended - Ultrasound: although oligohydramnios can support the diagnosis, its role in the primary diagnostic pathway is unclear compared to speculum and biochemical testing
Management
There are 3 main domains in the management of PPROM:
- Prophylactic antibiotic – ALL patients
- Maternal corticosteroid – selected patients
- Maternal magnesium sulfate – selected patients
Preterm labour vs P-PROM management:
- Maternal corticosteroid and magnesium sulfate therapy / indications are the same in P-PROM and preterm labour
- 2 major differences:
- Tocolysis is NEVER indicated in P-PROM, but may be used selectively in preterm labour
- Maternal intrapartum antibiotic prophylaxis is ONLY indicated for established preterm labour (but NOT P-PROM on its own)
- Oral erythromycin is ONLY indicated for P-PROM (but NOT preterm labour on its own)
1. Prophylactic Antibiotic
| Purpose | Reduce risk of chorioamnionitis |
| Indications | ALL patients with P-PROM |
| Choice of agent |
|
| Duration | Until labour or a maximum of 10 days (whichever is sooner) |
Co-amoxiclav should be avoided as it is associated with an increased risk of neonatal necrotising enterocolitis.
2. Maternal Corticosteroids
| Purpose | Primary benefits: stimulate surfactant production in the fetal lung → accelerate fetal lung maturation → reduce risk of neonatal respiratory distress syndrome
Also reduces the risk of intraventricular haemorrhageSteroids accelerate maturation of fetal vascular system, including fragile intracerebral vessels implicated in intraventricular haemorrhage. and necrotising enterocolitisThe anti-inflammatory effect of steroids is though to reduce inflammation in the gut thereby reducing risk of necrotising enterocolitis. |
| Indications | In short, indicated in <36 weeks of gestation
Exact recommendations:
|
| Choice of agent | IM betamethasone / dexamethasoneBoth agents readily cross the placenta
Do not give more than 2 courses of maternal corticosteroids for preterm birth |
| Duration | Standard: a single course which consists of 2 doses of corticosteroids
A single repeat course (another two doses) can be considered if the first course was completed more than 7 days ago and the woman is at very high risk of giving birth within the next 48 hours No more than two courses total should be given during a single pregnancy |
3. Maternal Magnesium Sulfate
| Purpose | Provide fetal neuroprotection – reduces risk of cerebral palsy
Magnesium stabilises neuronal membranes, reducing risk of excitotoxic injury |
| Indications | In short, indicated if <34 weeks of gestation
Exact recommendation:
|
| Choice of agent | IV magnesium sulfate (initial 4 g bolus over 15 min, followed by 1g / hour) |
| Duration | Until birth or for a maximum of 24 hours (whichever is sooner) |
Monitoring for clinical signs of magnesium toxicity in the mother at least 4 hourly:
- Deep tendon reflex (reduced deep tendon reflex) – the earliest and most sensitive indicator
- Blood pressure (hypotension)
- Respiratory rate (respiratory depression)
Management of magnesium toxicity: stop the magnesium infusion + IV calcium gluconate (antidote)
Timing of Delivery
Delivery timing depends on which week P-PROM occurred:
| Gestation | Recommendation |
|---|---|
| >34 weeks | Expectant management until 37 weeks
(unless there are additional indications for expedited delivery Such as: These necessitate a different management plan, often involving earlier delivery. |
| 34-37 weeks | Offer the option of:
While expectant management until 37+0 weeks is the primary recommendation (as it is generally associated with better outcomes), the choice between expectant management and induction is based on patient preference and clinical assessment of risks and benefits This incldues: |
IMPORTANT exception:
If the patient is a GBSGroup B Streptococcus - aka Streptococcus agalactiae carrier during the current pregnancy → immediate delivery (induction of labour or caesarean birth) + maternal IAPIntrapartum antibiotic prophylaxis with IV benzylpenicillin
See the Group B Streptococcus in Pregnancy article for more information.
Identifying Infection in P-PROM
The patient should be closely observed for, and advised to report the following clinical signs:
- Fever
- Malaise
- Lower abdominal pain
- Abnormal / offensive vaginal discharge
- Reduced fetal movements
Investigations:
- CRP
- White blood cell count
- Cardiotocography (signs of fetal distress or tachycardia can be an early indicator of intrauterine infection)
Preterm Labour
Prevention in High-Risk Women
4 key risk factors that determine if prophylactic treatment is necessary:
- History of spontaneous preterm birth (up to 34 weeks) or late pregnancy loss (16 weeks onwards)
- TVUSTrans-vaginal ultrasound shows cervical length ≤25 mm (carried out at 16-24 weeks of gestation)
- History of P-PROM in previous pregnancy
- History of cervical traumaExamples outlined by NICE: - Previous cone biopsy - Large loop excision of the transformation zone (LLETZ) - Radial diathermy
If the patient is at risk, consider the following prophylactic options:
- Vaginal progesterone (start between 16-24 weeks, until at least 34 weeks)
- Cervical cerclagetypically removed at 36–37 weeks of gestation, or earlier if there is spontaneous onset of labor, rupture of membranes, or a clinical indication for delivery
Disclaimer: this section provides a simplified version underpinning the rationale of the guideline instead of the exact recommendations.
Exact NICE recommendations on choosing the prophylactic options depend on what risk factors the patient has:
- Points 1 and 2 → offer a choice of either option
- Point 1 or 2 → consider vaginal progesterone
- Points 2 plus 3 or 4 → consider cervical cerclage
Assessment
If preterm labour is suspected clinically (from maternal history):
- Perform clinical assessment and a speculum examination
- Established labour is defined by the presence of regular contractions AND progressive cervical dilation from 4cm
Subsequent actions:
- If clinical assessment suggests preterm labour at <30 weeks → clinical diagnosis can be made (no diagnostic testing is necessary)
- If at ≥30 weeks → perform diagnostic testing
Diagnostic tests:
Do not use TVUSTrans-vaginal ultrasound and fetal fibronectin testing in combination to diagnose preterm labour.
- ONLY one of the following 2 tests should be used
- If TVUSTrans-vaginal ultrasound is NOT suggestive of preterm labour, do NOT perform further fetal fibronectin testing (as preterm labour is already considered unlikely)
| Test | Interpretation |
|---|---|
| 1st line: TVUSTrans-vaginal ultrasound | Measure cervical length:
|
| 2nd line (only if TVUSTrans-vaginal ultrasound is unavailable or unacceptable): fetal fibronectin testing* |
False +ve result may occur in the following instances:
|
*If a fetal fibronectin swab is planned, it must be taken before any digital vaginal examination due to risk of false +ve.
Management
There are 3 main domains in the management of preterm labour:
- Tocolysis – selected patients
- Maternal corticosteroid – selected patients
- Maternal magnesium sulfate – selected patients
Preterm labour vs P-PROM management:
- Maternal corticosteroid and magnesium sulfate therapy / indications are the same in P-PROM and preterm labour
- 2 major differences:
- Tocolysis is NEVER indicated in P-PROM, but may be used selectively in preterm labour
- Maternal intrapartum antibiotic prophylaxis is ONLY indicated for established preterm labour (but NOT P-PROM on its own)
- Oral erythromycin is ONLY indicated for P-PROM (but NOT preterm labour on its own)
1. Tocolysis
| Purpose | Suppress uterine contractions
Delays preterm delivery, usually up to 48 hours so that other interventions (e.g. steroids and magnesium sulfate) or transfer to a higher-level facility can be arranged |
| Indications | In short, indicated in <34 weeks of gestation WITH intact membranes
Exact recommendations:
|
| Choice of agent |
Beta-mimetics should NOT be offered as a tocolytic agent. |
Tocolysis should be avoided / NOT offered if ANY of the following:
- Ruptured membrane (due to increased risk of maternal chorioamnionitis)
- Suspected or confirmed intrauterine infection (e.g. chorioamnionitis)
- Presence of significant vaginal bleeding
2. Maternal Corticosteroids
| Purpose | Primary benefits: stimulate surfactant production in the fetal lung → accelerate fetal lung maturation → reduce risk of neonatal respiratory distress syndrome
Also reduces the risk of intraventricular haemorrhageSteroids accelerate maturation of fetal vascular system, including fragile intracerebral vessels implicated in intraventricular haemorrhage. and necrotising enterocolitisThe anti-inflammatory effect of steroids is though to reduce inflammation in the gut thereby reducing risk of necrotising enterocolitis. |
| Indications | In short, indicated in <36 weeks of gestation
Exact recommendations:
|
| Choice of agent | IM betamethasone / dexamethasoneBoth agents readily cross the placenta
Do not give more than 2 courses of maternal corticosteroids for preterm birth |
| Duration | Standard: a single course which consists of 2 doses of corticosteroids
A single repeat course (another two doses) can be considered if the first course was completed more than 7 days ago and the woman is at very high risk of giving birth within the next 48 hours No more than two courses total should be given during a single pregnancy |
3. Maternal Magnesium Sulfate
| Purpose | Provide fetal neuroprotection – reduces risk of cerebral palsy
Magnesium stabilises neuronal membranes, reducing risk of excitotoxic injury |
| Indications | In short, indicated if <34 weeks of gestation
Exact recommendation:
|
| Choice of agent | IV magnesium sulfate (initial 4 g bolus over 15 min, followed by 1g / hour) |
| Duration | Until birth or for a maximum of 24 hours (whichever is sooner) |
Monitoring for clinical signs of magnesium toxicity in the mother at least 4 hourly:
- Deep tendon reflex (reduced deep tendon reflex) – the earliest and most sensitive indicator
- Blood pressure (hypotension)
- Respiratory rate (respiratory depression)
Management of magnesium toxicity: stop the magnesium infusion + IV calcium gluconate (antidote)
Cervical Insufficiency and Emergency Cervical Cerclage
IMPORTANT: Emergency cervical cerclage is specifically indicated for premature cervical dilatation and is NOT a treatment for preterm labour.
Description
Purpose: performed for premature cervical dilatation
Description: a surgical procedure in which a suture is placed around the cervix to prevent further cervical dilatation and delay preterm birth
Indications
Indications (ALL of the following must be present):
- <28 weeks of gestation
- Dilated cervix
- Exposed and unruptured fetal membrane
Emergency cervical cerclage should NOT be offered if ANY of the following is present:
- Signs of infection
- Active vaginal bleeding
- Uterine contractions
Delivery of Preterm Babies (P-PROM and Preterm Labour)
Mode of Birth
Key takeaway: P-PROM / preterm labour on its own does NOT mandate a specific mode of birth for the baby’s benefit.
Discuss the general benefits and risks of caesarean birth and vaginal birth
- NICE particularly mentions the increased risk of classical incision while performing a caesarean birth of preterm birth
- Explain that risks are specific to gestational age, not mode of birth
Intrapartum Antibiotic Prophylaxis (IAP)
IAP is indicated for ALL established preterm labour to prevent neonatal GBS disease:
- This is irrespective of maternal GBS carrier status
- Rationale: ~22% of early-onset group B streptococcal disease cases occur in prematurely born babies, and the mortality rate is much higher for pre-term infants (20-30% vs 2-3%) [Ref]
Note that P-PROM on its own is not an indication for IAP (erythromycin is given instead).
It is the onset of preterm “labour” that necessitates IAP.
Cord Clamping
- Position the baby at / below the level of placenta before cord clamping
- Delayed cord clamping is recommended (wait at least 60 seconds)
- Unless there are specific indications for earlier clamping (e.g., need for immediate resuscitation)
Delayed cord clamping is the preferred approach for BOTH term and preterm neonates
Benefits of delayed clamping: [Ref]
- Term infants → reduces the risk of iron deficiency later in infancy
- Preterm infants
- Greater haemodynamic stability
- Reduced mortality rates before hospital discharge
- Reduced rates of IVHIntraventricular haemorrhage and NECNecrotising enterocolitis
References
NICE Guideline Preterm labour and birth
RCOG Guideline Care of Women Presenting with Suspected Preterm Prelabour Rupture of Membranes
NICE guideline Intrapartum care 1.7 Prelabour rupture of membranes at term
RCOG Green-top Guideline No. 36 Prevention of Early-onset Group B Streptococcal Disease