4.10 Threatened preterm delivery

Regular uterine contractions and cervical changes before 37 weeks LMP.

4.10.1 Risk factors

– Preterm rupture of membranes before 37 weeks LMP
– Maternal infection
– Pregnancy-related disorder (e.g. pre-eclampsia, polyhydramnios, placenta praevia)
– Multiple pregnancy
– Cervical insufficiency
– Age < 18 years
– Malnutrition

4.10.2 Management

– Look for and treat any maternal infection; always perform urinalysis (dipstick test); perform rapid malaria test in endemic areas. 

– Let the woman deliver:
• If > 34 weeks LMP and membranes have ruptured.
• If labour is too advanced to be stopped (cervix effaced, 5 cm dilation), no matter what gestational age.
• If the mother’s life is threatened (poor general condition, pre-eclampsia, eclampsia, abruptio placentae, severe haemorrhage, etc.), no matter what gestational age.
• If foetal death is confirmed (no foetal movements and no foetal heart tones at several checks or ultrasound confirmation of foetal death).

– Otherwise, try to stop the contractions:
• Strict bed rest in a medical setting. Bed rest alone may be enough for mild forms (contractions but no cervical changes).
• Tocolytic therapy:
The main objective is to postpone delivery in order to administer corticosteroids for accelerating foetal lung maturation.
nifedipine PO (immediate release tablet): 10 mg to be repeated every 15 minutes if uterine contractions persist (max. 4 doses or 40 mg), then 20 mg every 6 hours. Never administer sublingually (risk of placental hypoperfusion and foetal death); always use the oral route. Duration of the treatment is 48 hours.

– Prepare the foetus for preterm birth:
After 26 weeks LMP and before 34 weeks LMP, help lung maturation with dexamethasone IM: 6 mg every 12 hours for 48 hours. In case of severe maternal infection, start antibiotherapy prior to dexamethasone.

4.10.3 Preterm delivery

– Delivery is usually rapid and often breech.
– Avoid aggressive treatment (drugs or procedures), but above all, avoid a long labour. Expulsion should be rapid: consider episiotomy, even if the foetus is small; before 34 weeks LMP vacuum extraction is contra-indicated, use forceps if instrumental extraction is required.
Prepare for neonatal resuscitation (Chapter 10, Section 10.2). Closely monitor neonate's temperature (risk of hypothermia) and blood glucose (risk of hypoglycaemia).

4.10.4 Preventing preterm delivery

– Treatment of infections and other disorders during pregnancy.
Rest for women with predisposing factors: multiple pregnancy, polyhydramnios, previous preterm delivery.