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Flashcards in Normal labour** Deck (35):

during labour there is an interplay of which three factors

power - uterine contraction
passage - maternal pelvis
passenger - fetus


progesterone does what

what happens to the levels in labour

keeps the uterus settles and prevents formation of gap junctions and hinders contractibility of myocytes

goes down


oestrogen in labour

makes the uterus onctract
promotes prostaglandin production which produces more oestrogen


what does oxytocin do in labour

where is it synthesised

what happens to the number of oxytocin receptors

initiates and sustains contractions
acts on decidual tissue to promote prostaglandin release

directly in decidual and extra embryonic metal tissues and in the placenta

increase in myometrial and decidual tissue near the end of the pregnancy


how is labour initiated

change in oestrogen/progesterone ratio

fetal adrenals and pit hormones may control timing of onset of labour

myometrial stretch due to uterus getting bigger leads to excitability of myometrial fibres

mechanical stretch of cervix and stripping of metal membranes

fergusons reflex - increase oestrogen and increased prostaglandin release


other causes that lead to labour

pulmonary surfactant secreted into amniotic fluid stimulates prostaglandin synthesis

increase in production metal cortisol stimulates an increase in maternal estriol

increase in my-metrical oxytocin receptors and their activation results in phospholipase C activity and subsequent increase in cytosolitic calcium and uterine contraction


3 stages of labour consist of what

first - latent/active
second - cervix dilated to 10cm - delivery of baby
third stage - delivery of placenta and membranes


latent stage

mild irregular uterine contractions, cervix shortens and softens, duration variable


active phase

4cm on to full dilatation
slow descent of the presenting part
contractions progressively becomes more rhythmic and stronger


second stage of the labour starts with what
how long does it take
what can happen in low risk px

starts with complete dilatation of the cervix (approx 10cm)

in nulliparous women considered prolonged if it exceeds 3 hours with regional analgesia or 2 hour without

in multiparous women - consider prolonged if it exceeds 2 hours with analgesia or 1 without

in low risk vaginal examinations are not always carried out to assess time for full dilatation


what happens during the third stage of labour
management actions taken

delivery of the baby to expulsion of the placenta and fatal membranes

av duration 10 mins can be 3 min longer

spontaneous delivery of the placenta - be prepared
use of oxytocin drugs and controlled cord traction is preferred for lowering risk of post partum haemorrhage


active management of third stage

syntometrine 1ml ampoule given
oxytocin 10 units

cord clamping and cutting
controlled cord traction
bladder emptying


cervical softening

increase in hyaluronic acid gives increase in molecules among collagen fibres

decrease in bridging among collagen fibres gives decrease in firmness of cervix


cervical ripening

decrease in collagen fibre alignment
decrease in collagen fibre strength
decrease in tensile strength of the cervical matrix
increase in cervical decorin


braxton hicks contraction what
when do they start/are felt

tightening of the uterine muscles - thought to aid the body to help prepare for birth
can start 6 weeks into the pregnancy
not usually felt until second or third trimester

irregular, do not increase in frequency or intensity
resolve with ambulation or change in activity
relatively painless


true labour contractions feelings

like a wave
pain starts low, rises until a peak and then ebbs away
if you touch the mothers abdomen during one it feels hard

start about 5 mins apart


what causes true labour contractions

oxytocin causes uterus to contract
evenly spaced
get more intense and painful over time
tighten the top part of the uterus pushing the baby down


what do both kinds of contractions do to the cervix

promote thinning of the cervix


where is the pacemaker and what direction does the wave spread
how do the waves synchronise
normal contractions have what

region of tubal ostia, downward direction

both ostia

upper segment contracts and retracts, lower segment and cervix stretch, dilate and relax

fundal dominance with a regular pattern and an adequate resting tone


best type of pelvis t have

gynaecoid pelvis


anthropoid pelvis

oval shaped inlet with large AP dm and smaller transverse dm


android pelvis
who are more at risk of this type of pelvis

triangular or heart shaped inlet and is narrower from the front

african caribbean women


what does liquor do

nurtures and protects fetus and facilities movement


when does the membrane usually rupture

in the first stage


abnormal position

breech, oblique, transverse
occipital posterior


crowning of head - what happens

what may be required to prevent trauma to anal sphincters

labia are stretched to full capacity
largest dm of the fatal head is encircles by the vulval ring



what are the components of the bishop score

station in pelvis


analgesia in labour

paracetamol/co codamol
combined spinal/epidural


blood loss normal

<500mls normal
>500mls not normal


plane of separation of placenta
mechanics of placental separation
method of separation

spongy layer of decidua basalis

shearing force

methew duncan marginal most common type of separation


3 signs that indicate placental separation
how long does it take

uterus contracts, hardens and rises
umbilicord cord lengthens permanently
gush of blood variable in amount

5-10 mins after delivery, normal up to 30 mins


how is homeostasis achieved

tonic contraction - lattice pattern of uterine muscle strangulates the blood vessels

thrombosis of the torn vessel ends - pregnancy is a hyper coaguable state

myo tamponade opposition of the anterior/posterior walls


what is a puerperium
how long does it last

period of repair and recovery


what consists of puerperium

return of tissues to non pregnant state
loch - vaginal discharge containing blood, mucus and endometrial castings
rubra (fresh blood)
serosa - brownish red watery
alba - yellow
uterine involution
weight reduces
fundal height - umbilicus within pelvis in 2 weeks
endometrium regenerates by a week
diuresis commences 2-3 days post natally


physio in puerperium

lactation initiated by placental expulsion
decrease in oestrogen and prog
prolactin is maintained
colostrum rich in immunoglobulin - long term protective effect for the baby