Lecture 16 - Labour And Birth Flashcards
What is parturition?
Labour
What is the definition of labour?
The process by which the fetus and its supporting placenta and membranes pass from the uterus to the outside world
What are the 3 key processes that occur during labour?
Regular high intensity conntractions
Softening and dilatiation of the cervix
Rupture of the Fetal membranes
What is considered a miscarriage?
Before 22 weeks
What is considered premature or pre term labour?
Before 37weels
What is considered term labour?
37weeks +
What are the 3 stages of labour?
1 = contractions and cervical dilatation (latent phase and active phase)
- Fetal descent and delivery (baby is born)
3 = placenta delivered
How wide does the cervix dilate to in the first stage of labour?
10cm
What general changes occur in stage one of pregnancy to create the birth canal?
Pelvic ligaments soften due to progesterone
Inc myometrium contractions
Cervical dilation and effacement (thinning)
What triggers cervical softening/ripening?
Prostaglandins
What occurs at the cellular level in cervical softening/ripening?
Less collagen and inc gylcosaminoglycans
Collagen bundles loosen (dec aggregation)
Influx of inflammatory cells and inc NO output
What happens to the myometrium in pregnancy?
Gets thicker (hypertrophy)
What sort of contractions of the myometrium occur in early pregnancy?
Small practice contractions of low amplitude
Brixton-Hicks contractions which are more noticeable but not painful
These contractions can’t effect cervix
How are prostaglandins important in myometrium contractions in labour?
Enhance release of calcium from Intracellular stores
What type of hormone is oxytocin?
Where is it secreted from?
Peptide hormone
Posterior pituitary gland (made in hypothalamus)
What is the function of oxytocin?
Lowered threshold for triggering action potentials/contractions in the myometrium.
What is the name reflex that is a positive feedback mechanism in labour?
Ferguson reflex
What is the Ferguson reflex?
Baby pushes head against cervix
This activates stretch receptors leading to posterior pituitary releasing oxytocin
Oxytocin stims smooth muscle uterine contractions to occur
Causes baby to push harder against cervix …..etc
What is brachystasis?
Where the muscle fibres dont fully relax after each contraction in labour slowly shortening the uterus helping force the baby out
What is the second stage of labour?
What occurs?
Where the baby is delivered
Cervix fully dilatated (10cm) until fetus is born
How long does the second stage of labour ((delivery) occur in:
Multiparous women?
Nulliparous (primigravida)?
Multiparous = 1hr
Nulliparous = 2hrs