Pregnancy and birth Flashcards
How is labour initiated?
Increase in oestrogen pro-labour hormone.
decrease in progesterone pro-pregnancy hormone.
release of oxytocin by mother’s posterior pituitary gland and decidua releasing prostaglandins create uterine contractions.
mechanical stimulation of uterus and cervix caused by overstretching and pressure from pp.
Outline the latent phase of labour
Effacement of cervix, contractions, intensity varies
How is active labour diagnosed?
Painful regular contractions, cervical effacement, dilatation of cervix of 4cm or more.
Outline the first stage of labour
Established labour to full cervical dilatation
Vaginal examinations
Average is 0.5cm/hour
Outline the second stage of labour
From full dilatation to delivery of baby
Outline the mechanism of birth
Head at pelvic brim occipital transverse (OT) position.
Flexion of neck (suboccipitobregmatic).
Head descends and engages.
Head reaches pelvic floor - rotates to occipital anterior.
Head delivers by extension.
Head “restitutes” (comes in line with the shoulders).
Shoulders rotate into anterior/posterior diameter of pelvis.
Anterior shoulder delivered by lateral flexion from downward pressure on baby’s head.
Posterior shoulder by upward lateral flexion.
Outline the third stage of labour
Delivery of placenta
Inspection of placenta to ensure completion
How is the third stage of labour carried out?
Active management (CCT) - oxytocin i.m. given into maternal thigh causes sustained uterine contraction,
aids delivery of placenta and contraction of placental bed,
decreases risk of post partum haemorrhage. Or
Physiological: mother naturally expels placenta and membranes with contractions.
Why is the foetus monitored in labour?
to detect fetal hypoxia and deliver baby if needed
How is the foetus monitored?
Screening the fetal heart rate by:
Intermittent auscultation by Pinard or Sonicaid
CTG (cardiotocograph)
FBS (foetal blood sampling)
How is intermittent auscultation used to monitor the foetal heart rate?
Every 15 mins before and after a contraction during the first stage.
Every 5 minutes in the second stage.
Any abnormality heard would lead to the use of the CTG.
How is CTG used to monitor the foetal heart rate?
Continuous print out of fetal heart rate and contractions:
abdominal ultrasound detects cardiac movements and hence heart rate; a clip applied to the fetal scalp (FSE)
detects R-R wave of fetal ECG.
Most usual is the abdominal ultrasound.
How is FBS used to monitor the foetal heart rate?
CTG is highly sensitive but poorly specific. use of CTG increases caesareans sections for fetal distress therefore
need to check CTG findings with FBS.
How is an FBS taken and what are the contraindications?
Stab on fetal scalp, blood collected via a glass pipette, pH and base excess result.
Contraindications: infection e.g. HIV, hepatitis B, fetal bleeding disorder, prematurity less than 32 weeks.
