Labour

Question 1

Sequencing in a normal vaginal birth

Answer 1

1. Head floating, before engaged
2. Engagement, flexion and descent
3. Further decent, internal rotation
4. Crowning
5. Complete rotation, beginning extension
6. Complete extension
7. Restitution (external rotation)
8. Delivery of the anterior shoulder
9. Delivery of the posterior shoulder

Question 2

Possible presenting diameters of the average foetal skull

Answer 2

Nomal vaginal delivery -> Suboccipitobregmatic (vertex, flexed) - narrow

Other:
Submentobregmatic (face) - narrow
Occipitofrontal (Vertex military) - wide
Verticomental (Brow) - widest - Emergency C-section

Question 3

Changes to the myometrium leading up to spontaneous labour

Answer 3

Myometrium
- more stretchy and contractable
- gap junctions form between cells in the presence of oestrogen - allowing for a synchronised contraction wave

Question 4

Changes to the cervix leading up to spontaneous labour

Answer 4

Cervix
- decrease in collagen, increase in water - allows it to soften, efface and dilate (ripen)

Question 5

Changes to the hormones leading up to spontaneous labour

Answer 5

Hormones
- increased oestrogen
-> increased prostaglandins
-> formation of oxytocin receptors in myometrium (increased stimulation for contractions and cervical ripening)

Question 6

Oxytocin positive feedback loop

Answer 6

Baby pushes against the cervix causing it to stretch
->
Stretching causes nerve impulses to be sent to the brain
->
Brain stimulates oxytocin release at the pituitary gland
->
Oxytocin causes the uterus to contract
…

Question 7

Uterine muscle function

Answer 7

Strongest muscle in the body

Horizontal muscle fibres - thicker nearer the cervix.

Vertical muscle fibres - Located at the cranial end of the uterus.

During labour, vertical muscle contract to draw the horizontal muscles up. This causes the cervix to thin and dilate

Question 8

Latent phase of labour

Answer 8

A period of time, not necessarily continuous, when there are painful contractions, and some cervical change, including cervical effacement and dilatation up to 4cm.

Question 9

Established phase of labour

Answer 9

regular painful contractions, and progressive cervical dilatation from 4cm.
Now need continuous 1-2-1 midwife care

Question 10

Measuring the descent of baby’s head

Answer 10

Assessed during vaginal examination in relation to the ischial spine of the pelvis.

Station 0 = Baby’s head is level with the ischial spine of the pelvis
+/-3 depending on how many centimetres baby’s head is above or below this point
Commonly, first stage of labour is -1, second stage of labour it becomes +1.

Question 11

First stage of labour

Answer 11

Stage 1 - Onset of established labour to full dilation of the cervix (4-10cm)
-Descent of baby’s head into the pelvis
- Walking and mobilising/ water immersion is recommended in this stage to reduce duration of labour, risk of caesarean birth and the need for an epidural.

Question 12

Second stage of labour

Answer 12

Stage 2 - From full dilation to birth of the baby

Passive
Full dilation without involuntary expulsion contractions

Active
Full dilation with expulsive contractions/ maternal effort

Question 13

Third stage of labour

Answer 13

Stage 3 - From birth of the baby to expulsion of the placenta and membranes

Active management:
- uterotonic drugs (syntomentrine)
- Deferred clamping and cutting of the cord (prevents anaemia in the baby) >1min
- Controlled cord traction

Physiological management:
- no uterotonic drugs
- no clamping of the cord until pulsation has ceased
- delivery of the placenta by maternal effort

Active management reduces risk of post-partum haemorrhage and shorted the length of the 3rd stage. However, uterotonic drugs can cause nausea and vomiting.

Question 14

Monitoring of foetus in labour

Answer 14

Low risk pregnancy (>37weeks)
Intermittent osculation for foetal heart (HR 110-160) - using doppler USS/ Pinard stethoscope

High risk pregnancy
Continuous foetal monitoring using CTG

Question 15

Tearing in vaginal labour

Answer 15

70-80% first time births have 3rd degree tears

1st degree – vaginal mucosa only
2nd degree – vagina and perineum
3rd degree – vagina, perineum and rectum sphincter
4th degree – vagina to rectum

Episiotomy – decrease chance of 4th degree tear and improve recovery, decrease chance of incontinence

Question 16

Physiology of pain in the first stage of labour

Answer 16

Concerns uterine contraction and dilation of the lower uterus and cervix

Visceral pain - colicky, poorly localised

Carried via T10-L1
+/- L2-S1 because of pressure on other pelvic organs

Question 17

Physiology of pain in the second stage of labour

Answer 17

Added to pain from the first stage
Dilation and pressure on pelvic organs + pelvic floor

Somatic pain - sharp, well localised

Carried by - pudendal nerve, S2-4

Question 18

Factors affecting pain in labour

Answer 18

Position of baby
Size of baby
Pelvic anatomy
Strength of contraction
Complications – APH, uterine rupture, trauma
Previous experience & expectations
Other factors – anxiety, fear of pain, social factors, educational background, etc.

Question 19

Non-pharmacological pain relief in labour

Answer 19

Antenatal information and preparation
Support from a birthing partner
Massage
Hydrotherapy (birthing pool)‏
TENS
Acupuncture
Aromatherapy

Question 20

Pharmacological pain relief in labour - analgesia

Answer 20

Non-opioids - paracetamol

Entonox (50/50 Nitrous oxide and oxygen) quick on/off but causes dizziness, nausea and amnesia

Opioids - Diamorphine, Morphine, Fentanyl, Alfentanil, Codeine and Pethidine

Question 21

Pharmacological pain relief in labour - anaesthesia

Answer 21

Regional anaesthesia (preferred anaesthetics)
- Epidural (prolongs labour)
- Combined spinal and epidural
- Caudal
- Para-cervical infiltration

Complications - infection/ intrathecal migration of catheter/ haematoma/ neurological damage

Contraindications:
- anticoagulants/ bleed disorders
- local/ severe systemic infection
- local spinal surgery
- massive haemorrhage