3 - labour Flashcards
define term delivery
preterm delivery
very preterm delivery
term = 37-41 weeks preterm = 22-37 (24 = viability limit)
very preterm = 28-32 weeks
(extremely preterm = 22-28 weeks)
(moderate late preterm = 32-37 weeks)
key tissues involved in labour
cervis
myometrium/uterus
foetal membranes
3 stages of labour
1 - cervical changes
(ripening and effacement; uterine/ myometrial contractions; rupture of foetal membranes )
2 - delivery of an infant
3 - delivery of placenta
describe the cervical changes -ripening and effacement
cervical walls remodel –> thins and dilates – MMPs causes loss of ECM
rigid –> flexible
leukocyte (neutrophil) recruitment and inflammatory processes (PG-E2 and IL-8)
Describe the uterine contractions
key mediators
fundal dominance - start at top and squeeze down
as labour progresses - more coordinated and more powerful
key mediators
- increased PG F2alpha and E2 from foetal membranes
- increased oxytocin receptor
- increased CAPs (contraction associated proteins)
Describe foetal membrane rupture and what its caused by
water breaking
caused by inflammatory changes and membrane remodelling
- loss of strength due to changes in amnion basement component
- leukocyte recruitment
- more MMPs
- More PGs and interleukins
describe the haemostatic changes post delivery of the placenta
increased clotting throughout pregnancy to prevent maternal haemorrhage via the huge spiral arteries
powerful uterine contractions squeeze off the maternal blood supple to stop her bleeding out
the main biochemical processes of labour
NFkB
progesterone receptor
progesterone
(foetal CRH and PAF)
NFkB and its role in labour
pro-inflammatory TF
all pro labour genes bind NFkB
main mediator in labour
CRH and PAF and its role in labour
both stimulate (control?) labour PAF is a sign of foetal maturity - produced by the maturing lung
both rise in labour and cause a rise in : PGE2 and COX-2 and IL-1 beta
progesterone, PR and its role in labour
P = high in pregnancy
NFkB and PR oppose each other
decrease in P ACTIVITY initiates labour
PR-A and PR-B
PR-B mediates the effects of P in pregnancy
PR-B is down regulated and so the effects of P in maintaining pregnancy is reduced (actual P levels remain high)
PR-B decreases, PR-A remains high
— functional progesterone withdrawal –> labour
Therefore, knowing what can mediate labour, what could trigger labour
anything that increases CRH (e.g. stress, twins)
anything that increases myometrial contractions e.g. uterine stretch by twins
anything that initiates inflammatory cascades e.g. intra-uterine infection, bleeding
