Extreme Preterm Labour

Extreme preterm labour is labour before 28 weeks of pregnancy. These babies account for a large share of neonatal deaths and long term disability. In facilities without neonatal intensive care the practical limit of survival is about 28 weeks, in tertiary units it is 24 weeks, and babies born at 22 to 23 weeks seldom survive. Counselling, steroids, magnesium sulphate and transfer to a unit with neonatal intensive care are the priorities.

• Risk factors: infection and inflammation, cervical insufficiency, previous mid-trimester loss or early preterm birth, twin pregnancy, bleeding, membrane rupture, uterine anomaly.
• Survival at 24 weeks is much lower in low resource units than in tertiary units.
• Intrauterine infection is common.

Women have contractions, backache, pressure, bleeding or leaking fluid, and often few symptoms before advanced dilatation. Examination may show a dilated cervix with bulging membranes.

• Painless dilatation with prolapsing membranes suggests cervical insufficiency.
• Fever, uterine tenderness and foul discharge suggest infection.
• Differential diagnosis: threatened miscarriage, cervical insufficiency, abruption, chorioamnionitis, ruptured membranes, urinary infection.
• Complications: periviable birth, respiratory failure, intraventricular haemorrhage, necrotising enterocolitis, retinopathy of prematurity, bronchopulmonary dysplasia, sepsis, cerebral palsy, neonatal death, maternal sepsis and haemorrhage.

The approach is to confirm gestation and stage of labour and to look for infection and a reason that can be treated.

• Confirm gestation from the earliest scan; ultrasound for presentation, estimated weight, liquor, cervical length and cord.
• Sterile speculum examination for bulging membranes, bleeding and rupture; fetal fibronectin is unreliable at this gestation.
• Full blood count, C-reactive protein, urine culture, high vaginal and rectovaginal swab, malaria test, blood pressure, group and cross-match.
• Cardiotocography only from the gestation at which the family and clinicians would act on it.

The principle is individual counselling, preparation of the baby and delivery in the best equipped unit available.

• Supportive: transfer in utero to a tertiary unit; counselling with the parents about survival and disability (a senior obstetrician and paediatrician together); decide in advance whether the baby will be resuscitated; two cannulae; left lateral position; delayed cord clamping for 60 seconds if the baby is vigorous; plastic bag without drying for babies below 28 weeks; kangaroo mother care; skin to skin contact.
• Pharmacological: betamethasone 12 mg IM twice, 24 hours apart, from 24 weeks, and from 23 weeks after counselling where active care is chosen; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most (stop for absent patellar reflexes, respiratory rate below 12 per minute or urine below 30 mL per hour, with calcium gluconate 1 g IV over 10 minutes for toxicity); nifedipine 20 mg oral once then 10 to 20 mg oral every 6 to 8 hours for up to 48 hours (maximum 120 mg daily) if no infection or bleeding; indomethacin 100 mg rectal once then 25 mg oral 6-hourly for 48 hours before 32 weeks where nifedipine is contraindicated; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily plus azithromycin 500 mg oral daily for suspected infection; benzylpenicillin 5 million units IV then 2.5 million units 4-hourly until delivery for group B streptococcus; oxytocin 10 IU IM at birth; neonatal surfactant (poractant alfa 200 mg/kg endotracheal, then 100 mg/kg), caffeine citrate 20 mg/kg oral or IV loading then 5 to 10 mg/kg once daily, and CPAP at 5 to 6 cm water pressure.
• Procedures: vaginal birth for a cephalic fetus; caesarean section for breech, transverse lie or fetal indications after counselling (classical incision may be needed); rescue cerclage at 16 to 26 weeks with bulging membranes and dilated cervix when infection and labour are excluded (cefazolin 2 g IV once and indomethacin 100 mg rectal once).
• Special groups: between 22 weeks and 23 weeks and 6 days the decision for active care or comfort care is individual and is made with the parents; breech babies at 26 weeks or more may be delivered by caesarean section where neonatal care is available.
• Red flags: fever above 38 degrees Celsius, bleeding, cord prolapse, rupture of membranes, fetal bradycardia, maternal breathlessness on tocolysis.
• Follow-up: neonatal intensive care or kangaroo mother care; maternal review at 6 weeks; cervical length scans and early plan for the next pregnancy, including progesterone and cerclage when indicated.