Twin Pregnancy with Preterm Labour

Twin pregnancy with preterm labour is labour with regular contractions and cervical change before 37 weeks in a woman carrying twins. Many twin births are preterm. It results from uterine overdistension, infection, membrane rupture, cervical insufficiency and preeclampsia. It matters because twins born preterm have higher rates of respiratory distress, brain haemorrhage and death.

• Risk factors: monochorionic twins, short cervix, previous preterm birth, assisted conception, polyhydramnios, infection.
• Progesterone and cerclage do not reduce preterm birth in unselected twins.
• Steroids and magnesium reduce neonatal death and injury.

Women have regular tightenings or lower abdominal pain, backache, pelvic pressure, watery or bloody discharge and a firm uterus. Examination shows cervical shortening or dilatation.

• Contractions every 10 minutes or less.
• Cervix dilated 2 cm or more or effaced 80 percent.
• Differential diagnosis: Braxton Hicks contractions, urinary infection, abruption, chorioamnionitis, round ligament pain, labour from membrane rupture.
• Complications: preterm birth, respiratory distress syndrome, intraventricular haemorrhage, necrotising enterocolitis, neonatal sepsis, cerebral palsy, maternal pulmonary oedema with tocolytic drugs, death.

The approach is contraction assessment, speculum and ultrasound.

• Cardiotocography of both fetuses with tocography; sterile speculum for membrane rupture and cervical dilatation.
• Transvaginal ultrasound: cervical length (below 25 mm is short); fetal presentation and growth of both twins; amniotic fluid index.
• Fetal fibronectin or placental alpha microglobulin 1 test where available; urine dipstick and culture; high vaginal and rectovaginal swab; full blood count and C-reactive protein.
• Blood pressure and urine protein to exclude preeclampsia.

The principle is transfer to a unit with neonatal care, steroids and magnesium, short term tocolysis to allow them, and delivery planning.

• Supportive: admit; left lateral rest; avoid fluid overload; two cannulae; blood group and cross-match; inform the neonatal team for two babies; transfer in utero to a unit with neonatal intensive care if below 34 weeks.
• Pharmacological:
  • Betamethasone 12 mg IM twice, 24 hours apart, between 24 and 34 weeks and 6 days.
  • Magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks.
  • Nifedipine 20 mg oral once then 10 to 20 mg every 6 to 8 hours for up to 48 hours (avoid beta agonists because of pulmonary oedema risk).
  • Atosiban 6.75 mg IV over 1 minute then 18 mg per hour for 3 hours then 6 mg per hour for up to 45 hours where available.
  • Ampicillin 2 g IV 6-hourly plus erythromycin 250 mg oral 6-hourly for 7 days when membranes have ruptured.
  • Benzylpenicillin 5 million units IV then 2.5 million units 4-hourly in labour for group B streptococcus.
  • Oxytocin 10 IU IM at birth.
• Procedures:
  • Vaginal birth if the first twin is cephalic with continuous cardiotocography.
  • Caesarean section for first twin non cephalic or for obstetric indications.
  • Deliver the second twin by amniotomy and oxytocin once it is cephalic and engaged.
• Special groups: preeclampsia, chorioamnionitis or abruption stops tocolysis and requires delivery.
• Red flags: cervical dilatation of 4 cm or more, membrane rupture, bleeding, fever, fetal tachycardia, maternal breathlessness on tocolysis, abnormal tracing in either twin.
• Follow-up: neonatal intensive care for both babies; maternal blood tests and review at 6 weeks; cervical length scans and early booking in the next pregnancy.