labour Flashcards
1
Q
factors involved in initiation of labour (3)
A
- ↓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
- 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 - COX-2 → prostaglandin (PGE2) → ↓collagen, ↑leukocyte migration, cervical ripening, uterine contractions
- Fetal cortisol
a. CRH levels rise early in some cases of PTL
b. CRH shown to increase COX-2 and PG synthesis
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
3
Q
management of preterm labour (6)
A
- Cervical cerclage: suture to hold cervix closed
- Tocolytics: oxytocin receptor antagonists and CCBs e.g. nifedipine
a. Inhibit uterine contractions
b. Inhibit membrane activation
c. Inhibit cervical remodelling - Corticosteroids: accelerate lung maturity
- NSAIDs: inhibition of COX-1/2
- Progesterone: inhibit production of pro-inflammatory cytokines and prostaglandins within uterus and inhibits myometrial contractility
- Antibacterial therapy
4
Q
risk factors/causes of preterm labour (7)
A
- Previous preterm delivery
- Infection: contributes to 25% of PTB
- Uterine over-distension: multiple pregnancy, polyhydramnios
Stretch → ↑upregulation of contraction associated proteins: COX-2, OTR (oxytocin receptor) - Cervical weakness
- Uterine abnormalities
- Fetal and maternal stress
- Iatrogenic induction of labour e.g. in pre-eclampsia, haemolytic disease of the newborn
5
Q
mechanism of infection causing preterm labour
SAQ 2016
A
- Pathogens w no cell wall → TLR2/TLR6
- Gram +ve bacteria → TLR2/TLR1
- Gram -ve bacteria → TLR4
All activate NFkB → cervical ripening, fetal membrane remodelling, uterine contractions
6
Q
management of abnormal labour (4)
A
- Augmentation: oxytocin, if problem w power
- ARM: artificial rupture of membranes
- Operative vaginal delivery
By ventouse (vacuum-assisted delivery) or forceps
Risks: postpartum haemorrhage, fetal intracranial haemorrhage, facial/brachial palsy - Cesarean delivery