Preterm Labour in Premature Delivery

Introduction

Preterm labour refers to labour occurring after 28 weeks but before 37 completed weeks resulting in premature delivery.
The preterm newborn is at risk of death because all its body systems such as lungs, brain, digestive and immune systems are not fully developed.
There is increased susceptibility to infection and impaired clotting mechanisms.
The baby is also at risk of birth injuries such as cerebral haemorrhage because the fragile cranial bones do not provide sufficient protection for the brain.
Some risk factors for preterm labour include young age of mothers, poor socio-economic class and smoking.

Causes of preterm labour

  1. Maternal infections e.g. pyelonephritis, malarial
  2. Incompetent cervix
  3. Premature rupture of membranes
  4. Multiple pregnancies
  5. Abruptio placentae
  6. Diabetes mellitus
  7. Pre-eclampsia/eclampsia

Symptoms of preterm labour

  • Regular and painful uterine contractions or abdominal pains

Signs of preterm labour

  1. Small maturity
  2. Palpable regular uterine contractions
  3. Progressive effacement and dilatation of the cervix
  4. Ruptured membranes

Investigations

  • FBC
  • Fasting or Random Blood Glucose
  • Ultrasound scan (for those not in established labour) for Gestational age
  • Foetal lie
  • Presentation
  • Amniotic fluid volume
  • Placental site
  • Estimation of the foetal weight

Treatment for preterm labour

Treatment objectives

  • To stop uterine contractions if labour is not fully established
  • To allow foetal growth and maturation in utero if feasible
  • To promote foetal lung maturity (gestations 28-34 weeks)
  • To allow labour to progress if it is already well established
  • To treat any underlying cause (e.g. malaria, pyelonephritis)

Non-pharmacological treatment

  • Avoid sexual intercourse
  • Avoid strenuous physical activity
  • Bed rest
  • Cervical cerclage suture for cases diagnosed as due to incompetence

Pharmacological treatment

A. Tocolysis

Evidence Rating: [B]
Salbutamol, IV infusion,

  • 2.5 mg in 500 ml of Dextrose 5%;
  • Start infusion at 10 micrograms per minute (i.e. 2 ml per minute) and increase rate gradually according to response at 10 minutes intervals until contractions diminish, then increase rate slowly until contractions cease (Maximum rate 45 micrograms per minute);
  • Maintain rate for one hour after contraction has stoped, then gradually reduce by 50% every 6 hours; (Maximum duration 48 hours.)

Or

Evidence Rating: [A]
Nifedipine, oral,

  • 20 mg initially, then 20 mg after 90 minutes

If contractions persist therapy can be continued with 20 mg every 3-8 hours for 48-72 hours as tolerated by patient (max. 160 mg per day)
Note

Monitor blood pressure

Magnesium sulphate, IV,

  • 6 g intravenous load initial over 20 minutes, then 2 g infusion per hour

After

Infusion rate is based on response

B. Foetal lung Maturation with Antenatal corticosteroids Gestations between 28-34 weeks

Evidence Rating: [A]
Betamethasone, oral,

  • 0.6-7 mg every 24 hours (2 doses)

Or

Dexamethasone,

  • 6 mg 12 hourly for (4 doses)

Note

Treatment is most effective if delivery occurs at least 24 hours after the first dose of the medicine has been given and less than 7 days after the last dose of the medicine.

Caution

  • Avoid Dexamethasone or Bethamethsone use when infection is present.
  • Dangers of steroid use include susceptibility to infection, fluid retention and pulmonary oedema and maternal postpartum collapse.

Referral Criteria

Treatment is best done in a hospital where the facilities can support the adequate care of the preterm neonate.
Therefore, refer the mother if the clinic cannot adequately care for the immature neonate.
It is better to transfer the foetus in-utero to the referral centre.