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