Preterm Labour

Onset of regular uterine contractions with cervical change before 37 completed weeks gestation.

Risk factors include previous preterm birth (the strongest predictor), multiple pregnancy, uterine or cervical anomaly, cervical insufficiency, infection (chorioamnionitis, bacterial vaginosis, UTI), polyhydramnios, and antepartum hemorrhage.

Clinical assessment of contraction frequency and cervical examination (dilation, effacement)
Transvaginal ultrasound cervical length: a length under 15 mm supports a high risk of imminent delivery; a length over 15 mm makes preterm birth within 7 days unlikely
Fetal fibronectin (a biomarker present in cervicovaginal fluid), a negative result has a high negative predictive value for delivery within 7 to 14 days and can avoid unnecessary intervention; used particularly when cervical length is equivocal (15 to 30 mm)
Exclude and treat infection: MSU, high vaginal swab, and, where membranes are ruptured, assessment for chorioamnionitis (see PPROM entry)

Tocolysis to delay delivery by 48 hours, allowing time for corticosteroids and, where relevant, in-utero transfer to a unit with appropriate neonatal facilities: nifedipine 20 mg PO loading dose, then 10 to 20 mg PO every 6 to 8 hours (maximum 24 hour dose per local protocol, commonly up to 60 to 160 mg/day), or atosiban (oxytocin receptor antagonist) by IV infusion where available; tocolysis is generally not continued beyond 48 hours and is avoided where there are contraindications (chorioamnionitis, severe pre-eclampsia, abruption, or non-reassuring fetal status)
Corticosteroids for fetal lung maturation: betamethasone 12 mg IM, 2 doses 24 hours apart, given for anticipated preterm delivery between roughly 24 and 34+6 weeks (up to 35+6 in some protocols); a single rescue course may be considered if delivery remains imminent more than 1 to 2 weeks after an initial course, per specialist guidance
Magnesium sulfate for fetal neuroprotection: given before anticipated delivery under 30 to 32 weeks (threshold varies by protocol), typically 4 g IV loading dose over 15 to 30 minutes, then 1 g/hour maintenance, reduces the risk of cerebral palsy in survivors
Group B streptococcus prophylaxis if status unknown or previously positive: benzylpenicillin 3 g IV loading dose, then 1.5 g IV every 4 hours until delivery (alternatives per allergy status: cefazolin, clindamycin, or vancomycin depending on allergy severity and local resistance)
Antibiotics are not given routinely for preterm labor with intact membranes in the absence of confirmed infection, given lack of proven benefit and some evidence of harm in this specific context
Mode and timing of delivery individualized by gestation, presentation, and fetal status

Referral: obstetric-led care with neonatal team involvement; in-utero transfer to a tertiary unit with appropriate NICU facilities if delivery under roughly 27 to 28 weeks is anticipated and local facilities are insufficient.

Preterm Premature Rupture of Membranes

Also known as: PPROM

Rupture of the fetal membranes before 37 weeks gestation and before the onset of labor (PPROM), distinct from term PROM (see next entry).

Carries risks of chorioamnionitis, cord prolapse, placental abruption, and, with prolonged rupture at early gestations, pulmonary hypoplasia and limb contractures.

Sterile speculum examination (avoid digital vaginal examination unless labor is suspected, given infection risk) to visualize pooling of amniotic fluid in the posterior fornix, confirming the diagnosis
If not visually obvious, testing for placental alpha microglobulin-1 (PAMG-1) or insulin-like growth factor binding protein-1 (IGFBP-1) in vaginal fluid supports diagnosis where clinical assessment is equivocal
Ultrasound assesses liquor volume and fetal presentation
FBC and CRP support monitoring for evolving infection; high vaginal and low vaginal swabs for group B streptococcus and other organisms

Admission for close monitoring of maternal temperature, fetal heart rate, and signs of chorioamnionitis
Prophylactic antibiotics: erythromycin 250 mg PO qds for 10 days, reduces the risk of chorioamnionitis and prolongs latency to delivery (co-amoxiclav is specifically avoided given an association with neonatal necrotizing enterocolitis in the ORACLE trial)
Corticosteroids (betamethasone as above) for anticipated preterm delivery
Magnesium sulfate for neuroprotection if delivery under roughly 30 to 32 weeks is anticipated, as per Preterm Labour entry
Chorioamnionitis (fever, uterine tenderness, maternal or fetal tachycardia, offensive liquor) mandates prompt delivery regardless of gestation, alongside IV broad-spectrum antibiotics (commonly a combination such as IV amoxicillin/ampicillin plus gentamicin, or per local sepsis protocol) and supportive management as for sepsis (see that entry)
Expectant management is generally continued until 34 to 37 weeks in the absence of infection or other complication, balancing prematurity risk against infection risk, with the specific gestation threshold for planned delivery guided by local protocol and specialist input
Group B streptococcus prophylaxis in labor as per Preterm Labour entry

Referral: obstetric-led care with neonatal input; urgent escalation for any sign of chorioamnionitis.

Preterm Labour

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management