Labour Flashcards
What initiates labour?
increased oestrogen
decreased progesterone
myometrial stretch increases excitibility of myometrial fibres
mechanical stretch of cervix and stripping of foetal membranes helps
Fergusons reflex
What is Fergusons reflex?
fetal distention of the cervix or vaginal walls stimulates a neuroendocrine response that leads to oxytocin production which leads to contraction of the uterus
How does progesterone act in labour?
keeps the uterus settled
prevents the formation of gap junctions
hinders the contractibility of myocytes
How does oestrogen act in labour?
makes the uterus contract
promotes prostaglandin production
How does oxytocin act in labour?
initiates and sustains uterine contractions
acts on decidual cells to promote prostaglandin release
increase of receptors in myometrial and decidual tissue towards the end of pregnancy causes increased phospholipase C activity which increases Ca and contractibility
Where is oxytocin synthesised?
in decidual and extraembryonic fetal tissues and in the placenta
How does pulmonary surfactant help in labour?
stimulates prostaglandin synthesis
What does fetal cortisol do to the mother?
increases oestrogen
What cervical changes happen during labour?
increase in hyaluronic acid gives increase in molecules among collagen fibres
decrease in bridging among collagen fibres gives decrease in firmness of cervix
How does cervical ripening happen?
decrease in collagen fibre alignment and strength
decrease in tensile strength of cervical matrix
increase in cervical decorin
What type of collagen makes up the cervix?
type 1,2,3,4
What does a high Bishops score indicate?
more likely to go into labour
What 5 elements make up the Bishops score?
position effacement dilation station in pelvis consistency
What makes up the first stage of labour?
latent and active phases
Describe the latent phase?
mild irregular uterine contractions
cervix shortens and softens
may last a few days
Describe the active phase?
4cm -> full dilation
contractions become more rhythmic and stronger
slow descent of the presenting part
What is normal progress during the active phase?
1-2cm per hour
What makes up the second stage of labour?
full dilation (10cm) -> delivery of the baby
In nulliparous (first time) pregnancy when is 2nd stage of labour considered prolonged?
if exceeds 3 hours with analgesia
2 hours if no analgesia
In multiparous (previous) pregnancy when is 2nd stage of labour considered prolonged?
> 2 hours with analgesia
>1 hour without
When should the membranes rupture?
just before labour
What comprises the third stage of labour?
delivery of the baby to expulsion of the foetal membranes and placenta