Preterm Labour

Regular uterine contractions resulting in cervical change occurring before 37 completed weeks of gestation.

Etiology

  • Multifactorial and often idiopathic
  • Major etiologic pathways:
    • Infection and inflammation
    • Uterine overdistension
    • Decidual hemorrhage
    • Maternal or fetal stress
  • Often overlaps with preterm premature rupture of membranes (PPROM)

Maternal Factors

  • Previous preterm birth
  • Short cervical length
  • Genital tract infection
  • Low socioeconomic status
  • Smoking, substance abuse
  • Extremes of maternal age
  • Chronic medical diseases

Obstetric Factors

  • Multiple gestation
  • Uterine anomalies
  • Polyhydramnios
  • Placental abruption
  • Cervical insufficiency

Clinical presentation

Braxton Hicks contractions

  • 'False labour'
  • Tightening of the uterine muscles, thought to aid the body to prepare for birth
  • Can start 6 weeks into pregnancy but more usually felt in the third trimester
  • Irregular, do not increase in frequency or intensity
  • Resolve with ambulation or change in activity
  • Relatively painless

True labour contractions

  • Happen under the influence of the releas of oxytocin, which stimulates the uterus to contract
  • True labour is when the timing of the contractions become evently spaced, and the time between them gets shorter and shorter
  • Real contractions will get more intense and painful over time

Signs of the third stage

  • Expulsion of placenta usually 5-10 minutes after delivery, considered normal up to 30 minutes
  • Uterus contracts, hardens and rises
  • Umbilical cord lengthens permanently
  • Frequently a gush of blood variable in amount
  • Placenta and membranes appear at introitus

Investigations

  • Bishop's score is used to determine whether if it is safe to induce labour
    • Position, consistency, effacement, dilation, station in pelvis
  • Partogram: a graphic record of key data (maternal and fetal) contained onto one sheet, used to assess progress of labour i.e. cervical dilatation, fetal heart rate

Management

Analgesia in labour

Treatment of pain in obstetrics follows a similar 'pain ladder' to treatment of pain in the non-pregnant population:
  • Non-pharmacological methods
    • Exercise/movement
    • Heat e.g. warm bath, heat pack
    • TENs stimulation
    • Acupuncture
    • Hypnosis
    • Massage
  • Nitrous Oxide (Entonox or 'gas and air')
  • Simple analgesia
    • e.g. paracetamol
  • Opiate analgesia
    • Oral codeine phosphate
    • IV/IM Diamorphine
  • Epidural analgesia
    • Does not impair uterine activity
    • Associated with a longer second stage of labour
    • Does not increase chance of caesarean birth but there is a slightly increased chance of an operative birth
    • Complications: hypotension, dural puncture, headache, high block, atonic bladder
  • Pudendal nerve block

Delayed cord clamping

  • Immediate clamping of the umbilical cord can reduce the red blood cells an infant receives at birth by more than 50%, resulting in potential short‐term and long‐term neonatal problems
  • With delayed cord clamping a higher red blood cell flow to vital organs in the first week was noted, and term infants had less anaemia at 2 months and increased duration of early breastfeedin
  • Delayed clamping, should be carried out unless immediate resuscitation is necessary - from cessation of pulsations, or up to 3 minutes after expulsion

Skin to skin

  • Early placing of the naked baby on the mother’s chest (SSC) helps keep babies warm and calm and considered to improve other aspects of a baby's transition to life outside the womb

Active management of third stage

  • Includes prophylactic administration of syntometerine (ergometrine maleate and oxytocin) or oxytocin