Labour Flashcards
define term - how many pregnancies occur in the time frame
Term= 37-41 weeks;
90% of human pregnancies are delivered within this time frame.
define pre term
Pre-term= 22-37 weeks
define very pre term
Very pre-term= 28-32 weeks
Term and preterm labour differ mainly in….
the initiating factors
what are the key tissues involved in labour
Uterus and cervix
how do these tisues change throughout pregnancy
undergo a substantial
change in structure and functions
transition from what is needed for pregnancy to
delivery
define human labour
process of expulsion of the fetus and the placenta from the uterus.
what main events occur leading up to deilvery of infant
Cervical ripening and effacement (thinning)
Co-ordinated myometrial contractions
Rupture of fetal membranes
what main events occur after delivery of infant
Delivery of placenta
Contraction of uterus
what changes occur to the cervix in labour
Change from rigid to flexible structure;
dilates (becomes thinner and is stretched sideways)
remodelling of extracellular matrix; recruitment of leukocytes; inflammatory process
(PG E2, Il-8).
what is stage 2
delivery of infant
describe the myometrial contractions (where they occur)
Fundal dominance;
increased co-ordination and power of contractions.
(increased levels and activity of MMPs)
describe the rupture of fetal membranes (why it occurs/where)
Rupture of fetal membranes… Loss of strength due to changes in amnion basement component;
increased MMP activity
inflammatory changes and leukocyte recruitment;
what factors in the cervix regulate labour
prostaglandin E2, IL-8, MMPs
what factors in the myometrium regulate labour
increased oxytocin receptor
increased contraction associated proteins
increase prostaglandin E2
what factors in the fetal membrane regulate labour
inflammatory processes, prostaglandins, IL, MMPs).
how are cervical changes accelerated during labour
accelerated by increasing pressure of the fetal head on the cervix
which is caused by increasing the strength and decreasing the gaps between myometrial contractions.
what is unique about promoters of many pro-labour genes
Almost all pro-labour genes have NFkB binding domains
in their promoters
how can pro-labour genes affect cell expression
Modification of NFkB sites in promoter sequences leads to loss of expression in cells or in expression vectors
what type of environment Is linked with labour
Inflammatory changes are strongly linked with labour and activators of inflammation are readily linked with preterm labour.
what are the candidate initiators of human labour
CRH and PAF
what do CRH and PAF do
up-regulate inflammatory pathways in fetal pathways
both stimulate interleukin and prostaglandin production
where is PAF produced
lungs
where is CRH produced
placenta
what hormone sustains human pregnancy and how does its level change throughout pregnancy
Progesterone
the levels remain very high until after delivery of the placenta
the relationship between which to molecules drives labour
There is a mutually negative relationship between the progesterone receptors and NFkB
if High NFkB and low Prog rc
= active NFkB
then labour continues
why is blood lost in the uterine lumen
Spiral arteries are unable to vasoconstrict to decrease blood flow due to remodelling which means blood is lost into the uterine lumen
how is blood loss limited in this stage
INVOLUTION
Powerful uterine contractions of involution effectively close the spiral arteries
define involution
powerful contractions of the uterus, leading to a rapid decrease in overall size –
what is the first stage labour
begins with the onset of uterine contractions through the period of dilation of the os uteri
what is the second stage of labour
period of expulsion effort, beginning with complete dilation of the cervix and ending with the expulsion of the infant.
what is the third stage of labour
begins with the expulsion of the infant and ends with the completed expulsion of the placenta and the membranes.
how long does stage 1 of labour last
8h
how long does placental delivery take
30 mins
what is placental delivery associated with
very powerful contractions of the uterus, leading to a rapid decrease in overall size
(involution)
what is involution linked with
an increase in maternal oxytocin
if it does not occur spontaneously, an injection of oxytocin is required
What is meant by the term “effacement”?
The process of the cervix changing from a tubular structure to become a thinner flatter structure.
