Week 4A Stages of Labour and Care Flashcards

Anatomy and Physiology of Labour

• Labour involves regular, coordinated muscular contractions.
  • Effacement and dilatation of the cervix.
  • Expulsive contractions for birth of baby and placenta.
• Stages:
  • Stage 1: Uterine contractions cause effacement and dilatation.
  • Stage 2: Full dilatation to birth of baby.
  • Stage 3: Birth of placenta.
  • Stage 4: 'Golden hour' for uterine tone and recovery.
• Uterus:
  • Prevented by uterotonic inhibitors during pregnancy.
  • Braxton Hicks contractions are mild and irregular.
• Cervix:
  • Protects from microorganisms and retains fetus.
  • Softens and 'ripens' near term.
• Cervical ripening:
  • Increases in oestrogen and relaxin.
  • Nitric oxide levels increase.
  • Stretching releases Prostaglandin F_{2 \alpha} and Oxytocin.
• Initiation of labour is timed by fetus and maternal mechanisms.
  • Hormones: CRH, prostaglandins, oxytocin, oestrogen, progesterone, relaxin, nitric oxide.

Stages of Labour Overview

• Intrapartum period: Onset of labour to birth of baby and placenta.
• First Stage:
  • Definition: Onset of uterine contractions causing effacement and dilatation to 10 cm.
  • Latent phase: Early labour.
  • Active phase: More rapid dilation.
  • Transitional Stage: Changes in behavior and body language; intense time requiring support.
• Second Stage:
  • Definition: Full dilatation to birth of baby.
  • Passive phase.
  • Active phase: Contractions and maternal effort assist descent.
• Third Stage:
  • Definition: Separation and expulsion of placenta and membranes.
  • Managed actively (synthetic oxytocin) or physiologically (no intervention).
• Golden Hour (Fourth Stage):
  • First hour after birth for health of woman and baby.
  • Monitoring vital signs and adaptation.

The 5 P's

• Factors influencing labour progress:
  • Passage: Pelvis shape and soft tissue resistance.
  • Passenger: Baby's position, lie, attitude, presentation, presenting part, and size.
  • Powers: Uterine contractions and maternal effort.
  • Psyche: Maternal thoughts, feelings, and responses.
  • Problems: Physical, emotional, or psychological stress disrupting normal process.

First Stage of Labour

• Definition: Regular, painful contractions causing effacement and dilatation to 10 cm.
  • Can last up to 16 hours (or longer) for first baby.
• Latent Phase ('early labour'):
  • Up to 4 cm dilated, slow cervical changes.
• Active Phase ('active labour'):
  • 4 cm - 10cm dilated, rapid dilation.
• Transition:
  • Just prior to second stage.
  • Feeling distressed, exhausted.
  • Progress is not linear and varies for each woman.

Effacement and Dilatation

• Effacement: Thinning of cervix.
  • Non-pregnant cervix is 2-3cm thick = 0% effacement.
  • Paper thin = 100% effaced.
• Dilatation: Opening of cervical os.
  • Undilated/closed = 0cm.
  • Fully dilated = 10 cm.
• Primips typically require full effacement before dilation.
• Multis may dilate before significant effacement.

Uterine Contractions

• Effective contractions needed for effacement and dilatation.
• Processes:
  • Cervix softening.
  • Coordinated myometrium contraction.
  • Stronger contractions at fundus.
• Hormones: prostaglandins, oxytocin, oestrogen, progesterone, relaxin.
• Retraction of upper segment leads to effacement.
• Dilatation of external cervical os.
• Loss of operculum/show/mucous plug.
• Fetal head pressure releases oxytocin.

Fetal Membranes and Labour/Birth

• Forewaters protect from infection.
• Intact membranes spread contraction pressure evenly and avoid placental compression.
• Membranes rupture spontaneously (SROM) or artificially (ARM).
• Benefits of intact membranes:
  • Reduced infection risk.
  • Cushioning for fetus/cord/placenta.
  • Fetus rotation.
  • Reduced pain.

Assessing Progress of Labour

• Contractions:
  • Assess strength, intensity, length, and frequency.
  • Slowing/irregular contractions may indicate exhaustion or fetal positioning.
  • Vaginal discharge: Blood-stained mucous (SHOW).
  • Colour of ruptured membranes will be recorded (clear, green, brown, black, and red).
• Abdominal palpation:
  • Determines baby's position.
• Vaginal Examinations (VE):
  • Sound rationale is important.
  • Assess cervix position and presenting part descent.