Normal labour Flashcards
what are the 3 key factors in labour
power - uterine contraction
passage - maternal pelvis
passenger - foetus
role of progesterone before labour
keeps uterus settled - preventing formation of gap junctions in myocytes
role of oestrogen in labour
makes uterus contract by promoting prostaglandin production
role of oxytocin in labour
initiates and sustains contractions
acts on decidual tissue to promote prostaglandin release
where is oxytocin synthesised
decidual and extraembryonic foetal tissues and placenta
factors causing initiation of labour
change in oestrogen/progesterone ratio
foetal hormones
myometrial stretch
ferguson’s reflex
why are multiple pregnancy/larger babies more likely to have pre-term labour
increased myometrial stretch initiating labour earlier
what is ferguson’s reflex
neuroendocrine reflex - positive feedback of uterine contractions from pressure on cervix/vaginal walls
latent phase of labour
up to 4cm
established phase of labour
4-10cm
what is normal progress during established stage of labour
1-2cms/hour
second stage of labour
complete dilation of cervix-delivery of baby
what is prolonged second stage in nulliparous women
> 3 hours if analgesia
>2 hours if not
what is prolonged second stage in multiparous women
> 2 hours with analgesia
>1 hour if not
third stage labour
delivery of baby - expulsion of placenta and foetal membranes
how long is third stage of labour
3+ mins (average is 10 mins)
if placenta doesn’t pass within 1 hour, what should happen
prepare for removal under GA
what drugs can be used to promote third stage of labour
syntometerine (ergometrine aleate and oxytocin)
or
oxytocin 10u
what happens to cervix in first stage of labour
shorten and softens - due to increase in hyaluronic acid
what are Braxton-hicks contractions
non-painful ‘practice’ contractions, most common at 36 weeks
what is pacemaker of contractions in labour
tubal ostia - in infundibulum
start at both ostia and move down
normal lie of foetus
longitudinal cephalic presentation
occipito-anterior
head flexed
what is crowning
appearance of a large segment of fetal head at the intoitus
what is placental separation/abruption
separation of placenta from uterus before baby is born
3 signs indicating placental separation
uterus contracts, hardens and rises
umbilical cord lengthens permenantly
gush of blood
what volume is abnormal blood loss during labour
> 500 mls
