First stage

• Latent first stage:

  • Painful contractions (irregular)
  • Changes to the cervix - effacement and dilation up to 4cm
• Established (active) first stage of labour:

  • Regular, painful contractions
  • Dilation of the cervix from 4cm onwards
• Signs of labour:

  • Show - mucus plug from the cervix (prevents bacteria entering uterus during pregnancy)
  • Rupture of membranes
  • Regular, painful contractions
  • Dilating cervix on examination
• Assessment:

  • Review antenatal notes
  • Review contractions - how often, long and strong
  • Pain relief
  • Maternal observation including urine dipstick for protein
  • Any vaginal loss - show, liquor, blood, meconium
  • Ask about foetal movements
  • Abdominal exam + foetal heartbeat after contraction
  • Vaginal exam for effacement and dilation
• Cervix normally around 3cm in length

  Effacement = thinning and shortening of cervix during labour
• Partogram:

  • Started on all women in active labour - assessment of progress
  • Foetal and maternal observations
  • Contractions
  • Dilatation - should be 1cm/hour - if below line suggests failure to progress
  • Liquor - green, yellow or offensive are signs of foetal distress
  • Drugs given
• Monitoring:

  • Low risk women - intermittent auscultation after every contraction, for at least 1 minute, at least every 15 minutes
  • High risk - continuous CTG with 2 transductors - foetal heartrate and uterine contractions
• CTG recording:

  • Uterine contractions
  • Foetal heartrate - baseline, variability, accelerations and decelerations
  • Can then be classified as reassuring, non-reassuring or abnormal
• Obstetric pain ladder:

  1. natural methods - positioning, hydrotherapy, TENs, simple analgesics
  2. Entonox
  3. Epidural
  4. If epidural contraindicated or declined - PCA with fentanyl/remifentanil, IM or IV morphine or diamorphine, pethidine
• Entonox:

  • Inhaled nitrous oxide
  • 50% oxygen and 50% nitrous oxide
  • Short half life - peat effect in 20-30 seconds
  • Weak anaesthetic at high concentration
  • Analgesic + anxiolytic at low concentration
  • Increases endogenous endorphin release
  • Can make women feel lightheaded and dizzy
  • Possible nausea and vomiting
• Pethidine and diamorphine:

  • Usually given IM
  • Opioids
  • May cause nausea and drowsiness in the mother
  • Can cause respiratory depression in the neonate if given too close to birth
• Epidural:

  • Local anaesthetic and opioid into epidural space in the lower back
  • Anaesthetic options - levobupivacaine or bupivacaine, usually mixed with fentanyl
  • Need catheter inserting
  • Reversible loss of sensory and motor function
  • Adverse effects:
  • Headache (post dural puncture headache)
  • Hypotension
  • Significant motor weakness in the legs
  • Nerve damage
  • Prolonged second stage
  • Increased probability of instrumental delivery
• Length of first stage:

  • First labour - average 8 hours (unlikely over 18 hours)
  • Second and subsequent labour - average 5 hours (unlikely over 12 hours)
• Vaginal assessment:

  • Vaginal examination offered every 4 hours during first stage
  • To assess rate of cervical dilatation
  • Want 1cm/hour
• Failure to progress:

  • Less than 2cm of cervical dilatation in 4 hours, or slowing of progress in a multiparous woman
  • Crossing the alert line on a partogram is an indication for an amniotomy (artificially rupturing membranes) and repeat examination in 2 hours - if membranes not already ruptured
  • Crossing the action line means care needs to be escalated to obstetric led care
  • Oxytocin is used first line to stimulate uterine contracts during labour
  • Other options - instrumental delivery and caesarean section
• Oxytocin:

  • Recombinant hormone
  • Produced by hypothalamus and stored in posterior pituitary - released in pulses during childbirth
  • Oxytocin receptors in myometrium increase during pregnancy - increased strength and frequency of uterine contractions
  • Oxytocin regulated by positive feedback - head of foetus pushing on cervix signals release
  • Used first line to stimulate uterine contracts during labour - started at a low rare and titrated up
  • Aim for 4-5 contractions per 10 minutes
  • Too many contractions can result in foetal compromise - no opportunity to recover