Labour

Labour is divided into three stages:

• First stage
  Covers the process of cervical dilation (0-10cm).
  • Involves:
    • Cervical dilation
    • Cervical effacement
    • Desent of the presenting part
  • Normal progress
    Based on rate of cervical dilation, should be >1cm/hr.
    • 0.5cm/hr is 10^th centile, and is often accepted
• Second stage
  Covers full dilation to delivery.
  • Involves:
    • Flexion
    • Descent
    • Rotation of the presenting part
      Head moulds, flexes, and rotates through the birth canal.
      • Head should be delivered occiput-anterior (OA); i.e. face-down
      • Head has to rotate through the pelvis as the pelvic inlet is widest in the transverse diameter, and the outlet in the A-P diameter
  • Normal progress
    Delivery should occur:
    • Within 2 hours of full dilation without epidural
    • Within 3 hours with epidural
• Third stage
  Delivery of the placenta.

Abnormal Labour

Management of abnormal labour depends on stage:

• Abnormal S1
  • Trial of oxytocin
    ↑ rate of dilation.
  • LUSCS
    If concerns about:
    • Uterine rupture
    • Obstruction
    • Power of contraction
    • Foetus
• Abnormal S2
  • Trial of oxytocin
    ↑ uterine contractility.
  • Operative vaginal delivery
    Forceps, vacuum. Indications can be divided into:
    • Maternal
      
      • Exhaustion
      • Contraindication to pushing
        • HTN
        • Cerebral aneurysm
    • Foetal
      • Distress
        CTG, scalp pH, prolapse.
    • Failure to progress
      Arrested descent. May be due to:
      • Mento-anterior (MA)
        Failure to descend.
      • Occiput Posterior (OP)
        Failure to rotate.
      • Other
        Usually requires LUSCS.
  • LUSCS
• Abnormal S3
  Active management of S3 significantly reduces PPH and maternal mortality. Active management involves:
  • Prophylactic oxytocin
    Upon delivery of the anterior shoulder.
  • Early cord clamping
  • Controlled cord traction

Management of Foetal Distress

• Avoid aortocaval compression
• Supplemental oxygen
• Treat hypotension
• Cease oxytocin
  Generally decision of obstetric team.
• Consider tocolytics
  • Terbutaline 250μg SC/
  • Salbutamol 100μg IV
  • GTN 400μg SL
• Prepare for em LUSCS

Premature Labour

Premature:

• Labor occurs prior to 37 weeks gestation
• Birth occurs in ~10% of deliveries
  Associated with 85% of all perinatal morbidity and mortality, due to:
  • Respiratory distress syndrome
  • Intracranial haemorrhage
  • Ischaemic cerebral damage
    Intrapartum:
    • Hypoxia
    • Asphyxia
    • Hypotension
  • Hypoglycaemia

Management

Principles:

• Foetal protection
  • Antenatal corticosteroids
    • For women <34⁺⁶ and birth expected in <7 days
      Risk:benefit of precise timing varies.
    • ↓ Foetal morbidity and mortality by ↓ incidence of respiratory distress syndrome by:
      • Accelerating lung maturity
      • ↓ IVH
      • ↓ Necrotising enterocolitis
    • Betamethasone 11.4mg IM daily for 2 days
  • Magnesium
    • For women <30⁰
    • ↓ Risk of cerebral palsy and death in preterm infants
    • Administer within 4 hours of birth:
      • 4g over 20 minutes
      • 1g/hr thereafter
• Consider tocolytics to stop premature contractions
  Agents include:
  • Magnesium sulfate
  • Calcium channel blockers
  • Methylxanthines
  • Prostaglandin inhibitors
  • β-agonists
    • Evaluate for hyperkalemia if on treatment longer than 24 hours
  • Ethanol
    • Historical
    • Inhibits ADH, oxytocin, and myometrial contractility
• Consider epidural as anaesthetic technique
  • Reduces effects of systemic drugs on foetus
  • Improved foetal perfusion
  • May reduce incidence of ICH by allowing controlled delivery

Induction of Labour

Artificial techniques to initiate the process of labour. Induction is performed:

• For:
  • Pregnancy reasons
    • PD
    • Twin pregnancy > 38 weeks
    • PROM
      See premature rupture of membranes
    • FDIU
  • Maternal disease
    • Pre-eclampsia
    • Diabetes
  • Foetal
    • IUGR
• By:
  • Pharmaceutical means:
    • Intravaginal or endocervical prostaglandin
    • Intravenous oxytocin
      
  • Non-pharmaceutical means:
    • Membrane sweep
      Digital stimulation of the cervix to release endogenous prostaglandins.
    • AROM
    • Cervical ripening balloon

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References

1. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.