labour Flashcards

1
Q

factors involved in initiation of labour (3)

A
  1. ↓progesterone:↑oestrogen
    Functional progesterone withdrawal; multiple theories
    a.↑PR-A:PR-B (PR-A antagonistic)
    b. NFkB → ↓PR

Stretch of myometrium → upregulation of contraction associated proteins: connexins, COX-2, OTR

  1. Oxytocin → NFkB → COX-2, cytokines
    a. ILβ → drives further COX-2 and PGE2 production (augment response)
    b. ILβ → cervical ripening, fetal membrane changes
    c. IL-8 → inflammatory cell influx into cervix and myometrium
  2. COX-2 → prostaglandin (PGE2) → ↓collagen, ↑leukocyte migration, cervical ripening, uterine contractions
  3. Fetal cortisol
    a. CRH levels rise early in some cases of PTL
    b. CRH shown to increase COX-2 and PG synthesis
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2
Q

phases of parturition

A

Phase 0: progesterone → myometrial repression: firm & relaxed to accommodate growing fetus
Phase 1: myometrial activation, membrane activation (preparing for labour)
Phase 2: uterine contractions, cervical dilatation
Resembles inflammatory reaction: ↑cytokines (IL-1β, IL-6, IL-8), ↑prostaglandins, influx of neutrophils into uterus
Phase 3: uterine involution

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3
Q

management of preterm labour (6)

A
  1. Cervical cerclage: suture to hold cervix closed
  2. Tocolytics: oxytocin receptor antagonists and CCBs e.g. nifedipine
    a. Inhibit uterine contractions
    b. Inhibit membrane activation
    c. Inhibit cervical remodelling
  3. Corticosteroids: accelerate lung maturity
  4. NSAIDs: inhibition of COX-1/2
  5. Progesterone: inhibit production of pro-inflammatory cytokines and prostaglandins within uterus and inhibits myometrial contractility
  6. Antibacterial therapy
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4
Q

risk factors/causes of preterm labour (7)

A
  1. Previous preterm delivery
  2. Infection: contributes to 25% of PTB
  3. Uterine over-distension: multiple pregnancy, polyhydramnios
    Stretch → ↑upregulation of contraction associated proteins: COX-2, OTR (oxytocin receptor)
  4. Cervical weakness
  5. Uterine abnormalities
  6. Fetal and maternal stress
  7. Iatrogenic induction of labour e.g. in pre-eclampsia, haemolytic disease of the newborn
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5
Q

mechanism of infection causing preterm labour

SAQ 2016

A
  1. Pathogens w no cell wall → TLR2/TLR6
  2. Gram +ve bacteria → TLR2/TLR1
  3. Gram -ve bacteria → TLR4
    All activate NFkB → cervical ripening, fetal membrane remodelling, uterine contractions
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6
Q

management of abnormal labour (4)

A
  1. Augmentation: oxytocin, if problem w power
  2. ARM: artificial rupture of membranes
  3. Operative vaginal delivery
    By ventouse (vacuum-assisted delivery) or forceps
    Risks: postpartum haemorrhage, fetal intracranial haemorrhage, facial/brachial palsy
  4. Cesarean delivery
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