Who Needs a Caesarean Birth? Max Brinsmead PhD FRANZCOG May 2008

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

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

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

Estimating Birth Size Notoriously inaccurate: 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

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?

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

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