1. Who Needs a Caesarean Birth?
Max Brinsmead MB BS
May 2015

2. Factors which influence the outcome of a trial of labour
The Passage
The Passenger
The Powers
The Psyche

3. The Passages Stature (and maybe shoe size!) Shape of the pelvis
Gynecoid
Android
Anthropoid
Platypelloid
Pelvic joint changes and position in labour
Soft tissues
An effect from parity
Maternal obesity

4. The Passenger Size Presentation Position Attitude Moulding
Adversely affected by epidural anaesthesia
Attitude
Flexed or deflexed
Moulding
Does this change with gestation?

5. Estimating Birth Size Notoriously inaccurate: Need to consider:
Ultrasound measures abdominal circumference typically +/- 20%
That is 2880 – 4320 g for average 3.6 Kg baby
Need to consider:
BW of previous babies
Mother’s size and weight gained in pregnancy
Mother’s own birthweight
Ethnicity
Father’s size

6. Estimating Pelvic Size
Clinical pelvimetry
Unreliable
X-ray or CT pelvimetry
Abandoned
“The best pelvimeter is the baby”
Engagement of the head before labour
Engagement and descent in labour
“Trial of labour”
Pelvic soft tissues are more important?

7. The Powers The effect of parity Maternal age An effect from posture
Upright position in labour
Fetal back uppermost when lying
Induction of labour
Augmentation of labour
Amniotomy
Oxytocin infusion

8. The Psyche The place of birth Maternal anxiety Analgesia in labour
Preparation for birth
The role of a doula

9. Any Questions or Comments
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