Lecture 12: Childbirth

Question 1

When does childbirth occur?

Answer 1

From last mensturation:

• viable from 23/24 weeks on
• <37 weeks is preterm
• > 41 weeks is postdates

Question 2

What is labour?

Answer 2

Labour is the process which brings about the delivery of the fetus and the placenta from the uterine cavity

Question 3

What is the onset and signs of labour?

Answer 3

Onset: Complex and incompletely understood

Signs:

• Regular painful contractions
• Show (cervical mucous plug)
• Rupture of membranes
• Progressive cervical change (effacement/dilatation)

Question 4

What is the latent phase of labour?

Answer 4

<4cm Labour

• Early stage, before active labour
• Highly variable duration from 1-2 hrs to 10-12hrs or longer
• Effacement (nulliparous) and dilation of the cervix (3-4cm)
• Some descent of the head

Question 5

What happens in the active phase of labour that is important?

Answer 5

• 4cm<
• Start to have changes in fetal metabolism
• 3 Stages

Question 6

Whats the first stage of active labour?

Answer 6

• Regular, painful contractions
• Cervical dilatation >3-4cm and fully effaced to full dilatation (“10cm”) Arbitrary value..
• Descent of the fetal head

Question 7

What is the second stage of active labour?

Answer 7

- Full dilatation and birth of the baby:
Passive descent (epidural) or active pushing

Question 8

What is the third stage of active labour?

Answer 8

From birth of baby till expulsion of the placenta

Question 9

How does the third stage occur?

Answer 9

Myometrium contracts and occludes blood vessels. Therefore need tonic contraction post birth to prevent bleeding. Babies can tolerate transient / hours of contractions

Question 10

How is the third stage managed and what is the risk?

Answer 10

Physiological: No intervention, delivered by maternal effort (up to 60 mins)

Active management:

1. Ecbolic (meds to contract uterus)
2. Await signs of separation
3. Controlled cord traction

Post partum haemorrhage is the leading cause of maternal death worldwide.

Question 11

How is the fetus monitored?

Answer 11

• Intermitted auscaltation if no risk factors
• If risk factors then continuous cardioticograph (pressure and HR), Fetal HR varies with contractions, concern if changes are sustained

Question 12

What three factors that determine progress?

Answer 12

Passenger (diam of babys head)
Passage (dimension of the pelvis)
Power (Degree of force expelling baby)

Question 13

How can the passenger be examined?

Answer 13

Abdominal palpation

• Fetal lie
• Presentation
• Position
• Engagement
• Fetal size

Question 14

What is fetal lie, presentation, position, attitude?

Answer 14

Fetal lie: Relation to mother, i.e usually longitudinal
Presentation: Part coming first
Position: Relationship of fetal occiput (bone) to the maternal plevis i.e Occiput anterior is most optimal (narrowest)
Attitude: The degree of flexion of the fetal head (ideal = maximal flexion = smallest diameter)

Question 15

Why is the passenger component so important?

Answer 15

Because it describes the expected delivery route of the baby and how wide, the widest part will be

Question 16

What is neat about the babies head?

Answer 16

Cranial bones are not fused. Separated by sutures and fortanelles. Allows moulding of the head as it passes through the birth canal.

Question 17

What is engagement when it comes to the passenger?

Answer 17

Refers to how deep the presenting part is engaged in the bony pelvis upon abdominal palpation (i.e more palpable = more above the pelvis)

Question 18

Describe the passage, bony pelvis:

Answer 18

Inlet: Wider transverse diameter
Mid cavity: round
Outlet: Wider A-P diameter

Question 19

Describe the stages of fetal movement through the pelvis in the second stage:

Answer 19

Flexion
Internal rotation of head
Extension
External rotation of head

Question 20

What is a big consideration when to comes to the passage and what is station?

Answer 20

Ischial spines are a big consideration

• Station: Descent of the head on vaginal examination assessed with reference to the ischial spines

Question 21

What is power?

Answer 21

Contractions of the uterus that last 45-60 seconds every 2-3 mins

Generated by the top of the uterus

Question 22

Describe delivery

Answer 22

1. As babys head reaches perineum, it extends under the pubic symphysis to come out of the pelvis, crowns (+/- tear) and is born.
2. Head restitutes rotating 90 degrees to adopt the transverse position in which it entered the pelvis
3. The ant shoulder comes under the pubic symphysis first
4. The rest of the body follows

Question 23

Whats slow progress in an abnormal labour?

Answer 23

First stage: <2cm/4hr dilatation
Second stage: Active pushing >2hr (nulliparous), >1hr (parous)
Third stage: >30mins, but act earlier if haemorrhage

Aetiology: 3 P’s

Question 24

Whats the action for lack of power in slow progress?

Answer 24

Insufficient uterine activity

ACtion: Treat dehydration, analgesia, augment with oxytocin (POWER)

Question 25

Whats the action for passenger causing slow progress?

Answer 25

Malposition! i.e occiput post.

Action: Allow more time and power for rotation; (manual rotation if in second stage) -> may need C section

Fetal size: C section if too big

Question 26

Whats the action for issues with passage in slow progress?

Answer 26

Cephalo-pelvic disproportion (True CPD rare)

C section!!!!

Question 27

In slow progress occurs in second stage and station 0 (mid cavity) what can be done?

Answer 27

Forceps delivery or venouse

Question 28

Notes on forceps delivery:

Answer 28

• Quicker
• More maternal birth canal injuries
• BUT overall less neonatal birth injuries
• Safer for preterm

Question 29

Notes on ventouse delivery:

Answer 29

• Rotation possible

- More neonatal cephalohaemotomas