stages of labour Flashcards
progesterones influence on labour
keeps uterus settled
prevents formation of gap junctions
HINDERs contractility of myocytes
progesteron -> P -> prevents
oestrogens influence on labour
makes uterus contract
promotes prostaglandin production
oestrogens -> O -> opens
oxytocins influence on labour (+pathophysio ish)
initiates + sustains contractions
acts on decidual cells to promote prostaglandin release
- systhesised directly in decidual + extraembryonic fetal tissues + placenta
number of oxytocin receptors increases in myometrial + decidual cells near end of pregnancy
cervical softening in labour
increase in hyaluronic acid gives increase molecules among collagen fibres
-> decrease in bridging among collagen fibres decreases in firmness of cervix
signs of labour
a show = shedding of mucus plug from cervix
rupture of membranes
regular, painful contractions
dilating cervix on examination
latent 1st stage = painful regular contractions, changes to cervix, dilation up to 4cm
induction of labour
where labour is started artificially - happens in around 20% of pregnancies
guided by Bishops score
indication of induction of labour
- prolonged pregnancy - 1-2wks after the estimated date of delivery
- prelabour premature rupture of membranes, where labour does not start
- intrauterine death
maternal medical problems
- diabetic mother >38wks
- pre-eclampsia
- obstetric cholestasis
Bishops score
best + safest method to determine if safe to induce labour
- <=4 -> indicates unfavourable cervical ripening, UNLIKELY to start without induction
- >=9 -> cervix ripe/favourable, high chance of spontaneous labour
what is factors are used to create bishops score
dilation
effacement
station
cervical consistenct
cervi position
methods of induction of labour
membrane sweep - finger passed through cervix to rotate against uterin wall, separating chorionic membrane from decidua
vaginal prostaglandins E2 (NOT oral)
misoprostolol
oxytocin infusion
amniotomy
induction of labour method with bishops score >/< 6
<=6 = vaginal prostaglandins or oral misoprostol
> 6 = amniotomy + IV oxytocin
(>=9 indicates cervix is ripe/favourable = high chance of spontaneous labour)
complications of induction of labour
uterine hyperstimulation - prolonged + frequent uterin contractions
preterm labour rupture of membranes (PRROM) confirmation
(occurs in 2% of pregnancies but assoc with 40% of preterm deliveries)
confirming PPROM
- speculum exam to look for pooling of amniotic fluid in posterior vaginal vault
– avoid digital exam due to risk of infection
- use may also show olihohydramnios
management of preterm labour rupture of membranes (PRROM)
admit
monitor chorioamnionitis is not developing
oral erythromycin should be given for 10days
antenatal steroids
delivery should be considered at 34wks
- balance risk of maternal chorioamnionitis + risk of resp distress syndrome in neonate
when does delivery of baby normally occur + what are the stages of labour
labour + delivery normally occur 37 -42wks gestation
1st stage = from onset of labour (true contractions) until 10cm cervical dilation
2nd = from 10cm cervical dilation until delivery of baby
3rd = from delivery of baby until delivery of placenta
stages of first stage of labour
latent
- mild irregular uterine contractions, cervix shortens + softens
- duration variable - may last uncomfortable few days
active
- 4cms onwards to full dilation
- progresses arounf 1cm an hour, regular contractions
prolonged second stage criteria
In nulliparous considered prolonged if
>3hrs if there is regional analgesia or 2hrs without
Multiparous - >2hrs with regional analgesia, 1 without
3 Ps in failure to progress
power = inadequate contractions (frquency/strength)
passages = short stature, trauma shape
passenger = big baby, head-pelvis ration, malposition
3rd stage of labour
delivery of baby -> explusion of placenta + fetal membranes
average -> 10mins, can be 3+mins
after an hour, prolonged surgical removal
prolonged 3rd stage criteria
active management >30mins
(use of oxytocic drugs + controlled cord traction)
passive/expectant management >60mins
why is delayed cord clamping beneficial
immediate clamping can reduce RBCs an infant receives at birth by more than 50%
delayed –> more RBCs, less anaemia at 2months
- within 5mins - should be delay of 1-3mins
(unless immediate resuscitation is necessary)
4 classic signs indicating separation of the placenta + membranes in 3rd stage of labour
- uterus contracts, hardens + rises into abdo
- umbilical cord lengthens permanently
- a gush of blood variable in amount
- placenta + membranes appear at introitus
(plane of separation = spongy layer of decidua basalis)
active management of 3rd stage
IM oxytocin - helps uterus contract
careful traction of umbilical cord - guide placenta out
(shortens 3rd stage + reduced risk of bleeding - BUT assoc N+V)
who is active management of 3rd stage offered to
all women at risk of PPH
if haemorrhage
or >60min delay
braxton hicks contractions
occasional irregular contractions of uterus felt in 2nd or 3rd trimester
not true contractions - do NOT indicate onset of labour
irregular + DO NOT increase in frequnecy or strength
mx - relax + hydrate
true labour contractions
- under influence of oxytocin, which stimulates uterus to contract
- timing of contractions become evenly spaced, time - - between gets shorter - length of them also increases
- more intense + painful over time
analgesia options for birth
paracetamol/co-codamol
TENS
entonoz
diamorphine
epidural
partogram
graphic record of key data, both maternal + fetal
- used to assess progression of labour, dilatation, fetal heart beat
3 key factor labour
Power - uterine contraction
PAssage - maternal pelvis
Passenger - fetus
duration of contractions
initially 10-15secs, slowly builds up
types of pelvis
anthropoid pelvis - oval inlet
android pelvis - triangular/heart shaped inlet, narrower
gynaecoid pelvis - most suitable **
normal fetal position
cephalic presentation
occipito-anterior, head engages, flexed head
7 cardinal movements in mechanism of labour
- descent - to pelvic inlet
- engagement - 3/5ths of fetal head enter pelvis, fetal head engaged when at widest diameter of fetal head has entered brim of pelvis
- flexion - chin against chest
- internal rotation - fetal shoulder rotate 45’
- extension + crowning - emerges from vagina, at level of interoitus
6, restitution - head externally rotates
7. expulsion - anterior then posterior shoulder
how is haemostasis achieved post delivery
tonic contraction - lattice pattern of uterine muscle strangulates blood vessels
thrombosis of torn vessels - pregnancy is hypercoaguable state
what is lactation initiated by post childbirth
by placenta expulsion + decrease in oestrogen + progesterone
(during pregnancy, oestrogen + progesteron inhibit milk secretion by blocking prolactin release + making amary glands unresponsive to it)
preterm + postterm
pre-term <37wks
post-term - >42wks
