10.1 Parturition and Problems with Parturition Flashcards
What is parturition?
Transition from pregnant state to non-pregnant state
At what timing defines a spontaneous abortion (miscarriage)?
Before 24 weeks
What defines preterm delivery?
Before 36 weeks
What defines post term delivery?
After 42 weeks
What are the stages of parturition?
First stage - Creation of birth canal
Second stage - Expulsion of the foetus
Third stage - Expulsion of the placenta + Uterine contraction
What foetal positions are assessed?
Lie - Relationship to long axis of the uterus (usually longitudinal)
Presentation - what part is adjacent to the pelvic inlet (podalic/cephalic)
What occurs in stage 1 of parturition?
Cervical ripening
Generating force through contractions
What happens in cervical ripening?
Collagenase
Increased glycosaminoglycans and hyaluronic acid
(Triggered by prostaglandins)
What are Braxton Hick’s?
Practice contractions
What are contractions affected by?
Oxytocin - Lowers threshold for action potentials (frequency)
Prostaglandins - More calcium per action potential
What is the Ferguson reflex?
Oestrogen and contractions positively feedback on the posterior pituitary, leading to more oxytocin and prostaglandins and hence heavier contractions
What is stage 2?
Labour
What initiates stage 2?
Prostaglandins (unknown what stimulates these)
What happens in stage 3?
Uterus contracts hard
Shears off placenta and expels it
Further uterine contractions to compress blood vessels (reduces haemorrhage)
What can be done to further prevent haemorrhage in stage 3?
Oxytocic drug
Fundal massage
