Normal Labour Flashcards
When does normal labour occur?
After 37 weeks gestation
What is labour?
Fetus, membranes, umbilical cord and placenta expelled from uterus
Regular, painful uterine contractions w biochemical changes in cervical tissue (cervical dilatation and effacement)
What does progesterone do in labour?
Hinders contractility of myocytes - reduced excitability of uterus
What does oestrogen do in labour?
Makes uterus contract
Promotes prostaglandin production
What does oxytocin do in pregnancy?
Initiates and sustains contractions
Acts on decidual tissue to promote prostaglandin release
What initiates labour?
Degree of uncertainty
Change in oestrogen and progesterone ratio
Positive feedback by stretch of cervix - increases uterine contractions and oxytocin release
Oxytocin release promotes prostaglandin release - increases uterine contractions
What is latent phase of the first stage of labour?
Latent phase - cervix shortens and softens (effacement), mild irregular uterine contractions
What is the second stage of labour?
passage of fetus through birth canal
What is the active phase of the first stage of labour?
Active phase - 4cm onwards, contractions more rhythmic and stronger, slow descent of presenting part
- usually 1-2cm/hour
What does the second stage of labour start with?
10cm dilatation
How long does the second stage of labour take in a multiparous woman?
within 2 hours
How long does the second stage of labour take in a nulliparous woman?
within 3 hours
Describe the movement of the fetus during the second stage of labour.
1 - descent
2 - flexion - chin to chest
3 - internal rotation - head turns to face mums back
4 - extension and crowning - birth of presenting part (head)
5 - external rotation (face to the side again)
6 - lateral flexion (delivers anterior shoulder - expulsion)
What is the third stage of labour?
Delivery of the placenta
When does the third stage of labour occur?
Usually within 10 mins of baby (after 1 hour, prepare to remove under GA)
Where is the plane of separation for the placenta?
Spongy layer of decidual basalis
What can you do to decrease third stage time?Why?
Injection of oxytocin or syntometerine
Decreases time and incidence of PPH
What do you assess when examining cervix?
Station Position Firmness Dilatation Effacement
What happens to the cervix during labour?
Softens and shortens
Why does the cervix soften during labour?
Increase in hyaluronic acid - increase in molecules among collagen fibres and decreased bridging between fibres
What are Braxton Hicks contractions?
Tightening of uterine muscles
Should be painless
Usually in third trimester
‘practice’ contractions
What causes labour contractions?
Oxytocin release
Describe true labour contractions.
Evenly spaced (time between them gets shorter and shorter) More intense and painful over time Length of each increases (10 seconds to 45)
What do contractions do?
Tighten top of uterus pushing baby downwards into birth canal
What is normal fetal position?
longitudinal lie cephalic presentation (presenting part - vertex) occipitoanterior position (head engages occipitotransverse)
What is the puerperium?
Return of tissues to non pregnant state in 6 weeks
What happens in the puerperium?
Lochia
Lactation
Uterine involution
What is lochia?
Vaginal discharge with blood, mucus and endometrial castings
When does lochia occur?
10-14 days after birth
What are the different types of lochia?
rubra - fresh red
serosa - brownish, red, watery
alba - yellow
What is uterine involution?
Regression to (almost) pre pregnancy state
How long does uterine involution take?
Fundal height from umbilicus to within pelvis in 2 weeks
How long does it take the endometrium to regenerate?
7 days apart from placental site
What initiates lactation?
Placental expulsion (third stage of labour)
What do prostaglandins do in labour?
initiate uterine contractions and cervical ripening
