Premature rupture of membranes and preterm labour

• Premature rupture of membranes (PROM) is rupture of the amniotic sac before labour begins; when it occurs before 37 weeks it is called preterm prelabour rupture of membranes (PPROM).
• PPROM complicates up to 3% of pregnancies and underlies 30 to 40% of preterm births. ^[1]
• A sterile speculum showing pooling of amniotic fluid makes the diagnosis; if no pool is seen, IGFBP-1 or PAMG-1 testing of vaginal fluid is used; nitrazine is not recommended. ^[1][2]
• After PPROM, offer expectant management to 37 weeks when there is no contraindication, with prophylactic erythromycin 250 mg four times daily for up to 10 days or until established labour. ^[2]
• Antenatal corticosteroids are offered from 24 to 33+6 weeks (consider 34 to 35+6) when preterm birth is likely; magnesium sulfate is given before 32 weeks for fetal neuroprotection; tocolysis is generally not recommended in PPROM. ^[1][2][8]

By the end of this page you should be able to:

1. Define PROM and PPROM and distinguish them from preterm labour and term rupture of membranes.
2. Recognise the clinical features and risk factors of PROM and PPROM.
3. Diagnose membrane rupture with a speculum examination and the correct confirmatory tests.
4. Diagnose and grade suspected chorioamnionitis using clinical and laboratory findings.
5. Manage PPROM according to gestational age, following RCOG, NICE, ACOG and WHO guidance, including antibiotics, corticosteroids, magnesium sulfate and timing of birth.
6. Know when tocolysis is and is not used.
7. Apply group B streptococcal intrapartum prophylaxis to women with preterm labour or PPROM.
8. Discuss prognosis, complications and prevention.

Rupture of membranes can occur at any gestation. The classification matters because management and outcome change sharply with gestational age.

• Term PROM (or simply PROM): rupture of membranes at or after 37+0 weeks, before labour starts. About 8% of pregnancies are affected. ^[6]
• Preterm prelabour rupture of membranes (PPROM; also written P-PROM): rupture of membranes before 37+0 weeks, without established labour. It complicates up to 3% of pregnancies and underlies 30 to 40% of preterm births. ^{[2] [6]}
• Preterm labour with intact membranes: regular uterine contractions with cervical change before 37+0 weeks, membranes still intact.
• Suspected preterm labour / diagnosed preterm labour: NICE terms. Suspected means symptoms with a clinical assessment that has not excluded preterm labour; diagnosed means a positive diagnostic test (for example a cervical length of 15 mm or less) in a woman already in suspected labour.

This page deals with all rupture of membranes, since the diagnosis is the same at any gestation, but concentrates on PPROM and its link with preterm labour because that is where the evidence and the guidelines are richest. PROM at term is a separate decision about induction and is covered only where it affects the same pathways.

PPROM complicates up to 3% of pregnancies and is associated with 30 to 40% of preterm births across high-income settings. In the United States, preterm birth occurs in approximately 10% of births overall, and preterm rupture of membranes specifically complicates approximately 2 to 3% of all pregnancies. Whole-population figures from low- and middle-income settings are less precise, but preterm birth and PPROM together make up a large share of neonatal death and disability there. ^[1][5][6]

PPROM matters because its consequences run from the membrane to the baby: amniotic fluid is lost, the barrier between the fetus and the vaginal flora disappears, and the pregnancy continues as an open system. Risk is concentrated in the second trimester, when even a small loss of fluid can lead to pulmonary hypoplasia and skeletal compression.

The cause of spontaneous membrane rupture is multifactorial. It is not usually the result of a single visible tear. Several processes weaken the chorion and amnion: inflammation in the membranes, stretching of the sac, reduced collagen cross-linking, and apoptosis of the membrane cells.

Risk factors consistently identified across RCOG, NICE and ACOG sources include:

• Previous PPROM or preterm birth, the strongest historical risk factor.
• Urinary tract or genital tract infection, including asymptomatic bacteriuria and bacterial vaginosis.
• Multiple pregnancy, polyhydramnios and any cause of over-distension of the uterus.
• Cervical insufficiency or a short cervix, cervical trauma and previous cervical surgery.
• Vaginal bleeding in pregnancy or placental abruption.
• Nutritional factors such as low body mass index or poor nutritional status.
• Smoking and substance use.
• Invasive procedures such as amniocentesis, although the added risk is small.
• Low socioeconomic status and previous uterine surgery.

Several of these act through a shared pathway: inflammation of the membranes raises matrix metalloproteinases and weakens the collagen scaffold, so rupture follows either spontaneously or after a rise in intrauterine pressure.

When the membranes rupture, the pressure inside the uterus falls. The umbilical cord is no longer cushioned by fluid and can be compressed, especially during contractions or when the head is poorly applied to the cervix. That is the mechanism of the acute emergencies of PROM: cord prolapse, fetal hypoxia and, in the preterm group, the need for careful monitoring.

The second pathway is infection. With the barrier gone, vaginal organisms ascend into the uterine cavity. The first clinical expression is chorioamnionitis (infection of the amniotic cavity and its membranes), then neonatal sepsis, puerperal sepsis and, in the most severe form, adult respiratory distress in the mother. The risk of chorioamnionitis rises with the time the membranes are ruptured, which is why gestational age and elapsed time drive every later decision.

The third pathway is preterm birth itself. PPROM is not labour, but it frequently triggers it: the inflammatory mediators released by the membranes (notably cytokines and prostaglandins) stimulate uterine contractions and cervical ripening. Hence PPROM and preterm labour are managed as one spectrum rather than as separate diseases.

The classic symptom is a sudden gush of clear or slightly blood-stained fluid from the vagina, followed by a persistent trickle or wetness that the woman cannot control. Women often describe it as "my waters broke". Features that help distinguish it from urine or vaginal discharge:

• a sudden large volume rather than a slow seep,
• fluid that keeps coming, including when the woman stands up,
• no smell or a mild amniotic smell rather than the smell of urine,
• no urgency or dysuria, and
• loss of the sensation of the sac "popping".

Preterm rupture may present more subtly as dampness or constant leaking. Always ask about reduced fetal movements, bleeding, pain, temperature and any history suggesting infection.

• General and temperature. Check maternal temperature, pulse and blood pressure. Fever, tachycardia or uterine tenderness suggests infection.
• Abdominal palpation. Fundal height, lie, presentation and any tenderness. Repeated palpation of a mobile, unengaged head in a preterm woman is a risk factor for cord problems.
• Speculum examination (sterile). This is the examination that makes the diagnosis: visualising pooled amniotic fluid in the posterior fornix, often with a small ferning or pH test as a bedside adjunct. A sterile single-bladed speculum is used and digital vaginal examination is avoided unless labour is being assessed.
• Digital examination is done only when labour is suspected, because it introduces infection once the membranes are ruptured.
• Fetal assessment. Heart rate (cardiotocography in PPROM), movements and, later in gestation, the presence of fluid around the fetus on ultrasound as a proxy that membranes have resealed.

Several conditions can mimic membrane rupture, and several can coexist. The table covers the membrane itself and the labour state.

Chorioamnionitis is usually polymicrobial, arising from ascending vaginal flora. The diagnosis is clinical: fever is the single most reliable sign, supported by maternal tachycardia, fetal tachycardia, uterine tenderness and offensive or purulent liquor. Fever alone is enough in a woman with recent membrane rupture to treat, even if other signs are absent.

RCOG and NICE both stress that no single test diagnoses it. A combination of clinical assessment, maternal CRP and white cell count, and measurement of the fetal heart rate with cardiotocography is required, and each element must be interpreted together. When the results conflict, continue to observe and repeat the tests.

The risk rises with the length of time the membranes have been ruptured, so every woman with PPROM is reassessed regularly for temperature, pulse, fetal heart rate and liquidity of the liquor.

1. Confirm the diagnosis and gestational age before anything else. Gestational age drives every recommendation below.
2. Check for contraindications to continuing the pregnancy: chorioamnionitis, placental abruption, fetal compromise or distress, cord prolapse, labour that cannot be stopped.
3. If none are present, offer expectant management to 37+0 weeks, because continuing the pregnancy compared with early birth is associated with better outcomes. Women should be told what to watch for (fever, reduced movements, change in fluid, regular contractions) and who to call.
4. Start prophylactic antibiotics as below.
5. Consider antenatal corticosteroids and magnesium sulfate according to gestation.
6. Tocolysis is not recommended in PPROM (RCOG); the focus is on prolonging safely, not on stopping labour that has started.
7. Communicate with neonatologists and offer emotional support to the woman and her partner.

Care at home may be appropriate for some women once the initial 24 to 48 hours of observation have passed and the pregnancy remains stable.

The aim is to delay delivery and reduce infection, not to treat a known infection. NICE recommends:

• Oral erythromycin 250 mg four times a day, for a maximum of 10 days or until the woman is in established labour, whichever is sooner. ^[2]
• If erythromycin is not tolerated or is contraindicated, an oral penicillin for the same maximum of 10 days or until labour.
• Co-amoxiclav is not offered as prophylaxis for intrauterine infection. ^[2]

RCOG's equivalent advice is that an antibiotic, preferably erythromycin, is given for 10 days or until established labour, whichever is sooner. These are prophylactic courses. If chorioamnionitis is diagnosed, treatment becomes broad-spectrum intravenous therapy, not prophylaxis. ^[1]

ACOG notes that latency antibiotics containing ampicillin, when given in the setting of preterm prelabour rupture of membranes, are adequate for group B streptococcal prophylaxis.

Use the combination of clinical assessment, CRP, white cell count and fetal heart rate on cardiotocography. No single element is sufficient, and discordant results are an indication to continue observation and repeat the tests.

• Expectant management to 37+0 weeks is the default. ^[1]
• At 34 to 36+6 weeks with PPROM and group B streptococcal colonisation, bacteriuria or infection in the current pregnancy, NICE recommends offering immediate birth (induction or caesarean) to reduce early-onset neonatal infection.
• Beyond 37 weeks, PROM is managed according to term PROM pathways (induction within 24 hours, with the woman involved in the decision). ^[1]
• Throughout, fetal wellbeing, liquor and signs of infection guide rather than replace gestational age.

Tocolysis has one job in this setting: to delay birth briefly so that antenatal corticosteroids and magnesium sulfate can be given and the woman can be transferred to a centre with neonatal care. It has no proven effect on neonatal outcomes by itself, and no effect on making the pregnancy continue.

NICE's recommendation (for women with intact membranes) is:

• Nifedipine is offered between 26+0 and 33+6 weeks in suspected or diagnosed preterm labour. ^[2]
• Nifedipine is considered between 24+0 and 25+6 weeks in suspected preterm labour. ^[2]
• If nifedipine is contraindicated, an oxytocin receptor antagonist (atosiban) is offered. ^[2]
• Betamimetics are not offered.

WHO's 2022 tocolytic recommendation is a context-specific one: tocolytic therapy is used to delay birth so that a single course of antenatal corticosteroids can be completed or so the woman can be moved to a facility with adequate neonatal care. Magnesium sulfate has a tocolytic effect but other agents are more effective at delaying birth; availability, contraindications and cost decide which agent is used. ^[9]

Crucially, tocolysis is not recommended in PPROM (RCOG). The membranes are already ruptured; the aim is not to stop labour but to make the interval safe. Starting tocolysis in a woman with ruptured membranes risks masking chorioamnionitis and prolonging exposure to ascending infection. ^[7][8]

Antenatal corticosteroids accelerate fetal lung maturity and reduce respiratory distress, intraventricular haemorrhage and necrotising enterocolitis. They are the single most effective antenatal intervention for a preterm baby.

WHO 2022 recommends them from 24 weeks to 34 weeks when gestational age can be assessed accurately, preterm birth is highly likely within 7 days, there is no clinical evidence of maternal infection, and both the mother and the newborn can receive adequate care. The same guideline does not recommend them for women with chorioamnionitis who are likely to deliver preterm. ^[8]

NICE splits the gestational range a little differently:

• Discuss, and make a shared decision, at 22+0 to 23+6 weeks in suspected or established preterm labour, planned preterm birth or PPROM. ^[2]
• Offer routinely from 24+0 to 33+6 weeks in suspected, diagnosed or established preterm labour, planned preterm birth or PPROM. ^[1]
• Consider from 34+0 to 35+6 weeks in the same situations. ^[2]
• A single repeat course is considered under 34+0 weeks when a previous course was given more than 7 days ago and birth in the next 48 hours is very likely (take care when there is suspected fetal growth restriction or the woman is under 30 weeks). ^[2]
• No more than two courses in total. ^[2]

ACOG (patient guidance) frames the same range as 24 to 34 weeks for anyone at risk of delivery within 7 days, including those with ruptured membranes, with a possible offer up to 36+6 weeks and consideration from 22 weeks after discussion. A repeat course is offered when the prior one was more than 14 days ago. ^[5]

The conventional course is four doses of 6 mg dexamethasone given intramuscularly every 12 hours, or two doses of 12 mg betamethasone given 24 hours apart. ^[10]

Antenatal magnesium sulfate given shortly before a very preterm birth reduces the risk and severity of cerebral palsy in the surviving baby. It is started only when birth is likely within 24 hours. ^[11]

WHO recommends it strongly for women at risk of imminent preterm birth before 32 weeks, and NICE recommends: ^[7]

• Intravenous magnesium sulfate for neuroprotection is offered from 24+0 to 29+6 weeks in established preterm labour or a planned preterm birth within 24 hours. ^[2]
• It is considered from 30+0 to 33+6 weeks in the same situations. ^[2]
• At 23+0 to 23+6 weeks the decision is individual and shared with the woman and her family.
• Dose: a 4 g intravenous bolus over 15 minutes, then 1 g per hour until birth or for 24 hours, whichever is sooner.
• Monitor for toxicity with pulse, blood pressure, respiratory rate and deep tendon reflexes at least every 4 hours; withhold or reduce if oliguria or renal failure appears. ^[2]
• Magnesium is given for no more than 24 hours (MHRA guidance applies to prolonged or repeated use). ^[2][3]

International product guidance lists three intravenous regimens used in practice (4 g over 15 to 30 minutes then 1 g per hour for 24 hours is one of them) and no evidence currently favours one regimen over the others. ^[11]

When a woman presents with suspected preterm labour and intact membranes, NICE recommends:

• Clinical assessment, then transvaginal cervical length at 30 weeks or above: more than 15 mm makes preterm labour unlikely; 15 mm or less supports diagnosed preterm labour. Under 30 weeks, after assessment, treat according to the preterm pathways.
• Fetal fibronectin (concentration more than 50 ng/mL supports preterm labour; 50 ng/mL or less makes it unlikely) is used when cervical length is not available, not both together.
• Treat according to the sections on tocolysis, corticosteroids and magnesium sulfate.
• Bed rest and hydration are not effective for preventing preterm birth and are not recommended (ACOG). ^[5]

Antibiotics in preterm labour with intact membranes do not prolong pregnancy and do not improve neonatal outcome; they are not used for tocolysis. Where there is a specific bacterial infection, treat that. ^[5]

Group B streptococcus (GBS) is the leading cause of early-onset neonatal infection. About 50% of colonised women transmit the organism to the baby, and without intrapartum prophylaxis 1 to 2% of those babies develop early-onset disease. Gestation under 37 weeks, prolonged rupture of membranes, chorioamnionitis and low birth weight all raise risk. ^[4]

ACOG (Committee Opinion 797, reaffirmed 2025) recommends universal vaginal-rectal culture at 36 to 37 weeks; women who are positive receive intrapartum prophylaxis unless a planned prelabour caesarean is performed with intact membranes. Women with a known GBS in a previous pregnancy who have not had a negative culture this pregnancy are also treated. ^[4]

NICE (neonatal infection guideline NG195) offers intrapartum antibiotics to women, trans and non-binary birthing people who are:

• in preterm labour, or
• have GBS colonisation, bacteriuria or infection in the current pregnancy, or
• had GBS colonisation, bacteriuria or infection in a previous pregnancy without a negative culture this pregnancy, or
• had a previous baby with invasive GBS infection, or
• have a clinical diagnosis of chorioamnionitis.

NICE's first-line intrapartum antibiotic is benzylpenicillin, with a cephalosporin such as cefotaxime if there is a non-severe penicillin allergy, and regimens including vancomycin for severe allergy. Where chorioamnionitis is diagnosed, gentamicin and metronidazole are added. The first dose is given as soon as possible after labour starts, or as soon as infection is suspected, and continued until birth. ^[3]

ACOG and NICE agree that at least 4 hours of antibiotic exposure before birth is desirable, with at least 2 hours reducing colony counts; obstetric interventions should not be delayed solely to reach 4 hours. ^[4]

In PPROM specifically, at 34 to 36+6 weeks with GBS colonisation, bacteriuria or infection in the current pregnancy, NICE recommends immediate birth to reduce early-onset neonatal infection (34 to 37 weeks). Latency antibiotics containing ampicillin, when used in PPROM, are adequate for GBS prophylaxis. ^[3][4]

• Chorioamnionitis: see above. Risk rises with duration of rupture.
• Neonatal sepsis and early-onset group B streptococcal disease.
• Preterm birth and its complications: respiratory distress syndrome, intraventricular haemorrhage, necrotising enterocolitis, retinopathy of prematurity.
• Cord prolapse and fetal hypoxia in the minutes after rupture.
• Placental abruption, which can follow or precede PPROM.
• Oligohydramnios and pulmonary hypoplasia after second-trimester PPROM.
• Maternal infection (endometritis) after birth.
• Recurrence in later pregnancies.

Prognosis depends principally on gestational age at rupture and at birth. The later the gestation, the better the outlook: from 34 weeks the outlook is excellent if infection is avoided. Expectant management to 37 weeks gives better outcomes than early birth when there is no contraindication. Second-trimester PPROM carries the highest risk of neonatal death and of pulmonary hypoplasia.

Second pregnancies after PPROM carry a raised risk of recurrence, and women should be counseled accordingly, with surveillance in later pregnancies.

• Screen all pregnant women for asymptomatic bacteriuria with a urine culture early in pregnancy and treat it, since untreated bacteriuria can progress and trigger membrane problems. This is covered in the MedGrasp topic on urinary tract infection in pregnancy.
• Treat genital infections (bacterial vaginosis, sexually transmitted infection) in pregnancy as a matter of routine care.
• Avoid smoking, maintain nutrition and manage chronic disease.
• In women with a previous PPROM or a very short cervix, offer prophylactic vaginal progesterone from 16 to 24 weeks or prophylactic cervical cerclage where both a history of preterm birth and a cervical length of 25 mm or less at 16 to 24 weeks are present (NICE NG25). ^[2]
• In PPROM (not just preterm labour), consider prophylactic cerclage for women with a previous PPROM or cervical trauma and a cervical length of 25 mm or less on ultrasound at 16 to 24 weeks.

• Children and adolescents. Management follows the same adult pathways with paediatric input. Preterm labour in an adolescent is an infection risk and a safeguarding consideration, not just an obstetric one.
• Older adults. These women more often have comorbidity (hypertension, diabetes) that changes both the urgency of delivery and the speed with which corticosteroids are justified.
• Pregnancy itself is the special group this whole page addresses.
• Immunocompromised women need earlier and broader investigation of infection and lower thresholds for admission.
• Multiple pregnancy is one of the most common settings for PPROM and shortens fetal salvage gestations; management thresholds are the same by gestational age, but delivery is more difficult and neonatal care needs scale up.

• A sterile speculum examination is available everywhere and is the diagnosis. IGFBP-1 and PAMG-1 tests are often not available; in that case the diagnosis rests on examination and, if needed, observation.
• Erythromycin 250 mg four times a day for up to 10 days is cheap and widely available; an oral penicillin is the fallback. Co-amoxiclav is avoided.
• Dexamethasone (four doses of 6 mg intramuscularly 12 hours apart) is inexpensive and is the antenatal steroid most easily stockpiled; WHO's conditions for use (accurate gestation, birth likely within 7 days, no clinical infection, adequate care available) apply especially because infection and wrong dating are common where care is limited. ^[8]
• Magnesium sulfate as a 4 g intravenous loading dose over 15 minutes followed by 1 g per hour is cheap and is the neuroprotective dose with the strongest evidence base where infusion monitoring is available; the MHRA warning about toxicity monitoring applies. ^[2]
• Where gestational age is uncertain, the practical rule is to treat on the basis of the best estimate, and to err on the side of giving corticosteroids when birth looks imminent.

• RCOG Green-top Guideline No. 73 (2019, reviewed 2024) is the principal PPROM guideline: sterile speculum diagnosis, IGFBP-1 or PAMG-1 as confirmatory tests, combination assessment of chorioamnionitis, erythromycin for 10 days, expectant management to 37 weeks, "tocolysis is not recommended", corticosteroids and magnesium sulfate considered. ^[1]
• NICE NG25 (2015, last updated 2022) supplies the dose-level detail throughout: diagnosis, erythromycin 250 mg four times daily for up to 10 days, nifedipine tocolysis between 24 and 33+6 weeks, corticosteroid windows, and intravenous magnesium sulfate 4 g then 1 g per hour.
• ACOG Practice Bulletin No. 217 (2020) frames PPROM prevalence at 2 to 3% of pregnancies, latency antibiotics including ampicillin, and management by gestational age. ACOG Practice Bulletin No. 171 (2016, interim update) and the ACOG patient education page supply the corticosteroid, magnesium, tocolysis and bed-rest recommendations. ACOG Committee Opinion No. 797 (2020) is the basis of the group B streptococcal section: 1 to 2% early-onset disease without prophylaxis, universal screening at 36 to 37 weeks, 2 to 4 hours of antibiotic exposure desirable.
• WHO recommendations (2015 and 2022) supply the gestational windows for antenatal corticosteroids, the tocolytic context-specific recommendation, and the magnesium-sulfate recommendation before 32 weeks. The magnesium intravenous regimes quoted are from the WHO prequalification recommended summary of product characteristics for magnesium sulfate. ^[9]
• NICE NG195 (2021, updated 2026) supplies the intrapartum antibiotic table for group B streptococcal prophylaxis, including the benzylpenicillin-first choice and the chorioamnionitis combination.

Related MedGrasp topics, listed as plain text: urinary tract infection and pyelonephritis in pregnancy; diabetes in pregnancy; preeclampsia, HELLP and eclampsia; gestational and chronic hypertension in pregnancy; group B streptococcal disease in the newborn; pregnancy diagnosis and physiology; preterm birth; fetal growth restriction.