Normal Labour Flashcards
when does labour typically occur?
between 37 and 42 weeks gestation
what is labour?
a physiological process during which the fetus, membranes, umbilical cord and placenta are expelled from the uterus.
where does labour occur? and which is most common place for it to happen
- Consultant Led Unit
- Midwife Led Unit
- Homebirth
(96%- in hospital)
what occurs to oestrogen: progesterone ratio in labour?
oestrogen increases: progesterone decreases
role of progesterone in labour?
Progesterone settles the uterus and prevents it from contracting, prevents formation of gap junctions, hinders the contractibility of myocytes
during labour the oestrogen/progesterone levels change
-high levels of progesterone throughout pregnancy stops labour from being induced
Progesterone= Prevents
role of oestrogen in labour?
makes the uterus contract and promotes prostaglandin production
role of oxytocin in labour?
initiates and maintains uterine contraction
-Oxytocin is synthesized directly in decidual and extraembryonic fetal tissues, and in the placenta
where is oxytocin synthesised?
Oxytocin is synthesized directly in decidual and extraembryonic fetal tissues, and in the placenta
what initiates labour?
Change in oestrogen/progesterone ratio (progesterone decreases)
-Fetal adrenals and pituitary hormones may control timing of the onset of labour
-Myometrial stretch increases excitability of myometrial fibres
-Mechanical stretch of cervix and fetal of membranes
-Ferguson’s reflex
what is Ferguson’s reflex?
Oxytocin stimulates contractions, this pushes baby’s head on cervix which triggers further oxytocin production
role of pulmonary surfactant on initiation of labour?
Pulmonary surfactant secreted into amniotic fluid has been reported to stimulate prostaglandin synthesis
prostaglandins cause contractions
role of foetal cortisol on initiation of labour?
increase of foetal cortisol, increases maternal oestrogen (increasing ostrogen: progesterone and inducing labour)
what cervical changes are seen before inducing labour?
Cervical softening
Cervical reopening
explain how cervical softening occurs?
increase in hyaluronic acid will decrease bridging among collagen fibres, decreasing firmness of the cervix
explain how cervical reopening occurs?
changes include a decrease in collagen fibre alignment and strength, decrease in tensile strength of the cervical matrix, and an increase in cervical decorin
Excess of cervical decorin near term is capable if initiating a decorin-collagen interaction that leads to collagen fibril disruption and decreased cervical tensile strength
What scoring system is used to decide if it’s safe to induce labour?
Bishops score
how many stages of labour are there?
3
what is the first stage of labour made up of?
Active and latent phase
what occurs in the latent phase of labour and how long does it occur?
-mild irregular uterine contractions
-cervix shortens and softens
-cervix is dilated up to 3 or 4cms
-0.5cm dilatation per hour
-duration variable (may last a few days)
how does the latent phase of a first time mother tend to differ?
it tends to be longer
what is the size of the cervix at full dilatation?
10cms
what occurs in the active phase of labour and how long does it occur?
-cervix dilated from 4cms to full dilatation (10cms)
-Slow decent of the presenting part
-Contractions progressively become more rhythmic and stronger
-1 to 2 cm dilatation per hour
-This is the stage most women need analgesia for
what is the management for the active phase of labour?
-Normal progress is assed at 1-2cms per hour
-Analgesia, mobility and parity increase variability
how dilated are women in 2nd stage of labour?
fully dilated (10cms) to delivery of baby
