Labour Flashcards
Define term
37-41 weeks
Define pre and very pre term delivery
premature= 22-37 weeks
very premature= 28-32
what are the key tissues involved in labour?
Cervix
myometrium
fetal membranes
What are the key stages of labour?
Cervical ripening and enffacement coordinated myometrial contraction Rupture of fetal membranes Delivery of the infant Delivery of the placenta contraction of the uterus
How long do the three phases of labour last
Phase 1- contractions 12-48hrs
Phase 2 Delivery of the baby- a few hours
Phase 3 Delivery of the placenta - 30 minuets
Describe cervical ripening and effacement
Change of cervix from rigid to flexible, remodelling of ECM, leucocyte recruitment (mainly neutrophils). Inflammatory changes (PgE2, IL8 paracrine)
What causes water breaking
Rupture of the fetal membrain due to changes in amnion basement component, inflam and leucocytes, increased MMPS.
What mediates myometrial contractions?
PgF2a and PgE2 from fetal membrane, oxytocin recptor and contraction associated proteins.
What binding domain can be found in most pro labour genes
NFkB
What do ‘we’ think intiates term labour?
PAF- produced in the lungs (indicates fetal maturity)
CRH- produced by the placenta
Note both cause an increase in IL1B, pgE2, COX
What can predispose the initiation of labour
Anything that can increase CRH. Eg
multiple pregnancies, stress, infection.
What reduces the blood lost from spiral arteries
Strong uterine contractions during placental delivery as the spiral arteries cannot constrict to limit it.
also involution post placental delivery (oxcytocin mediated)
What accelerates cervical dilation?
Increased strength and frequency of contractions, forces the fetal head to put pressure of the cervix.
When do progesterone levels drop
Post placental delivery, before would lead to the end of pregnancy.
Why does labour occur when progesterone levels are still high?
At term more progesterone A is produced than B
progesterone B is the form that mediates the main effects of progesterone.
