Normal Labour Flashcards
what is labour?
Labour is the process in which the foetus, placenta and membranes are expelled via the birth canal. In normal labour this process occurs spontaneously, at term (37-42 weeks gestation), with the foetus presenting by the vertex and results in a spontaneous vaginal birth (SVD).
describe the initiation of labour
There are multiple theories and hypotheses, but we currently do not fully understand the aetiology of
labour. The physiological factors that cause labour to start are triggered by paracrine and autocrine
signals generated by maternal, foetal and placental factors which interplay. Two key physiological
changes must occur to allow for foetal expulsion of the foetus:
1. Cervix softens and this
2. Myometrial tone changes to allow for coordinated contractions
Progesterone decreases whilst oxytocin and prostaglandins increase to allow for labour to initiate.
describe the latent 1st stage of labour
A period during which there are intermittent, often irregular, painful contractions which bring about some cervical effacement and dilation up to 4cm
describe the established 1st stage of labour
Regular, painful contractions that result in progressive effacement and cervical dilation from 4cm.
The cervix is fully dilated at 10cm. Anticipated progress 0.5 – 1.0 cm per hour.
length of established 1st stage of labour
The length of established first stage of labour varies between but for a primigravida this stage lasts on average 8 hours (unlikely to last longer than 18hr) and for a multigravida this stage lasts on average 5 hours (unlikely to last over 12hr).
why does the length of 1st established phase of labour change between primigravida and multigravida
This change in time occurs because for the first baby the cervix thins first then dilates but in a multigravida women these processes occur together.
what is the 2nd stage of labour?
full cervical dilation to the birth of the baby
describe the passive 2nd stage of labour
The finding of full dilation of the cervix before or in the absence of involuntary expulsive contractions. Plan to allow one hour of passive second stage to allow for further foetal descent.
describe the ativea 2nd stage of labour
This is when the presenting part is visible. Expulsive contraction with a finding of full dilation of the cervix. Active maternal effort following confirmation of full dilation of the cervix in the absence of expulsion contraction.
how long should the active 2nd stage last?
In a primigravida birth you would expect birth within 2 hours of active second stage commencing and for a multigravida should be within 1 hour.
what is the 3rd stage of labour?
from birth of baby to the expulsion of the placenta and membranes
active management of the 3rd stage
- Routine use of uterotonic drugs
- Deferred clamping and cutting of the cord
- Controlled cord traction after signs of separation of the placenta
passive management of the 3rd stage
- No routine use of uterotonic drugs
- No clamping of the cord until pulsation has stopped
- Delivery of the placenta by maternal effort
when would you diagnose prolonged 3rd stage?
Diagnose a prolonged third stage of labour if it is not completed within 30 minutes of the birth with active management or within 60 minutes of the birth with physiological management.
progress and monitoring during labour
• Blood pressure, pulse, temperature, respirations, oxygen saturations, urine output, urinalysis
• Abdominal palpation
o Used to assess foetal lie, presentation, attitude, denominator, position, and engagement
• Vaginal examination
o Used to assess presentation, engagement and station, position, cervical effacement and dilation and presence/absence of membranes
• Monitoring of liquor (colour, smell, volume) once spontaneous or artificial rupture of membranes has occurred
o Should be colourless/straw coloured
o May be blood stained if happens quickly ideally small
o Meconium
• Auscultation of the foetal heart
o Either intermittently with hand held Doppler or Pinards, or continuously with CTG (cardiotocograph) monitoring
o Intermittently – every 15 mins in first stage and every 5 mins in the second stage
• Palpation of uterine muscle contractions
o Aiming for 3-4 every 10 mins, lasting approx. 40-60 seconds moderate to strong in strength
• External signs e.g. Rhomboid of Michaelia and anal cleft line
• The above should be documents on a partogram once established labour is confirmed
