Parturition Flashcards
Define pre-term, term and post-term gestation periods
- pre-term: 24-37 weeks gestation
- term: 37-42 weeks
- post-term: after 42 weeks
What are the things you can use to confirm the gestational age?
- using pregnancy wheels, adding 280 days to LMP (last menstrual period) to find EDD
- EDD (estimated date of delivery): dates or scan (LMP + 9 months + 7 days)
- ultrasound scan
- SFH: height measured from pubic symphysis to top of uterus
Describe the most common cephalic presentation of babies
- the back of the baby’s head faces the mother’s front (occiput anterior)
- the occiput is the determining point of the cephalic presentation
Describe diagnosing labour
History:
- labour pains
- show (mucus plug)
- sudden loss of fluid from the vagina
Abdo exam:
- uterine contractions
- frequency (3 every 10 mins)
- duration (40-60s)
- severity (>80mmHg)
Pelvic examination:
- cervical dilatation (opening)
- effacement (thinning of cervix)
- consistency
- position
- level of presenting part
Describe the stages of labour and the physiology behind it
- 0: quiescent - maintained by progesterone and relaxin
- 1: initiation of parturition, extending to complete cervical dilatation - increase in gap junction connectivity (prostaglandins), increase in oxytocin receptor numbers (oestrogen)
- 2: active labour, from complete cervical dilatation to delivery - oxytocin release triggered by the Ferguson reflex, prostaglandins
- 3: from delivery to expulsion of the placenta and final uterine contractions - oxytocin
What are the inhibitory factors of pregnancy that keep the stage of labour at 0?
- progesterone
- prostacyclin
- relaxin
- NO
- PTH related peptide
- corticotropin- releasing hormone
- human placental lactogen
What are the uterotropin factors that help activate labour?
- oestrogen
- progesterone
- prostaglandins
- corticotropin-releasing hormone
What are the uterotonin factors that maintain the stimulation of labour (phase 2)?
- prostaglandins
- oxytocin
What are the factors that maintain involution of labour (phase 3)?
- oxytocin
- thrombin
Describe the positive feedback loop of oxytocin during labour
- nerve impulses from cervix transmitted to brain
- brain stimulates pituitary gland to secrete oxytocin
- oxytocin carried in bloodstream to uterus
- oxytocin stimulates uterine contractions and pushes baby towards cervix
- head of baby pushes against cervix
(loops back)
Describe the events occuring at the 3 stages of labour
- stage 1: the cervix relaxes, causing it to dilate and thin out
- stage 2: uterine contractions increase in strength and the infant is delivered
- stage 3: the placenta is expelled
What defines the latent phase of labour and the active phase?
- latent: <4cm dilation
- active: 4-10cm dilation (and rupture of membranes)
Describe flexion during the second stage of labour/delivery
uterine contractions push the foetus downwards, while the cervix resists resulting in increased flexion of the head
Describe the pelvic stations
- measured in stations and describes the level at which the baby’s head is at
- (-3) is when the head is above the pelvis
- 0 is when the head is at the bottom of the pelvis
- +3 is when the head is crowning
What is an episiotomy and when is the procedure done?
- an incision made in the perineum to enlarge the opening for the baby to pass through
- done when the baby needs to be quickly delivered
