Flashcards in Labour Deck (18)
How many conceptions (within 13 weeks) end in early miscarriage per year in the UK?
How many late miscarriages are there per year in the UK?
What proportion of births are through labour (including emergency Caesarean section) and what proportion are via elective C-section?
Labour - 75%
Elective C-section - 25%
What proportion of pre-term deliveries are through labour and what proportion are via emergency C-section?
Labour - over half
Emergency C-section - under half
Describe the physical appearance of the baby at the end of normal (term) labour.
- wet (with wet hair)
- tension in its limbs
- air bubble at the mouth (indicates crying)
- head is the size of an adult hand
- body is the size of an adult forearm
Describe the physical appearance of the baby at the end of pre-term labour.
- all body structures are developed
- needs help breathing (and possibly other things)
- head is much smaller than an adult hand
What is the medical definition of labour?
Fundally dominant contractions, coupled with cervical ripening (softening) and effacement (thinning). The fundus is at the top of the uterus, so the contractions squeeze the baby down. The lower portion of the uterus and cervix must become loosened to allow for delivery.
What are the random, intermittent contractions that begin roughly 8 weeks before labour known as?
Describe the phases of labour.
- last many hours and involves contractions becoming more powerful and coordinated
- cervical ripening and effacement
- variable length (12 to 48 hours)
- may last hours
- baby is delivered
- approximately half an hour long
- placenta is delivered
List some initiators of pre-term labour.
- intrauterine bleeding
- multiple pregnancy
- maternal stress
What are the stages of labour?
1. Cervical ripening and effacement
2. Coordinated myometrial contractions
3. Rupture of foetal membranes
Describe the changes occurring in cervical ripening and effacement.
- structure becomes less rigid and more flexible
- loss of ECM
- recruitment of neutrophils
- production of PE2, IL-8 (local paracrine changes)
Describe the changes occurring during coordinated myometrial contractions.
- fundal dominance
- increased power and coordination
1. PF2a levels increased from foetal tissues
2. Oxytocin receptor upregulated
3. Contraction associated proteins
Describe the changes occurring during rupture of foetal membranes ('water breaks').
- loss of strength due to changes in the amnion basement component
- modest leukocyte recruitment in normal labour, exacerbated in pre-term
- increased levels and activity of MMPs
- inflammatory processes in foetal membranes
What is the role of NFkB in labour?
NFkB is part of the classic pro-inflammatory cascade of events. It upregulates cytokines, chemokines, adhesion molecules and COX-2 enzyme. It seems to switch on enzymes and processes that are key for labour (almost all pro-labour genes have NFkB binding domains in their promoters), which is why it is so hard to stop labour once it has begun.
Which 2 factors may be used to mimic changes in tissues during labour?
- Corticotrophin releasing hormone (CRH)
- Platelet activating factor (PAF)
CRH and PAF could upregulate all the pro-inflammatory cytokines, PGs and COX-2.
How do CRH levels change?
It rises steeply in the last 3-4 weeks of pregnancy. Simultaneously, a binding protein decreases, leaving more free CRH. COX-2 enzymes increase in the run up to labour.