normal labour Flashcards
what happens at the initiation of labour
- Change in estrogen/progesterone ratio
- 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 does progesterone do during the onset of labour
keeps the uterus settles
-prevents formation of gap junctions
-hinders the contractibility of myocytes
what does estrogen do during the onset of labour
makes the uterus contract and promotes prostaglandin production
what does oxytocin do during the onset of labour
initiates and sustains contraction, acts on decidual tissue to promote prostaglandin release
other things can can help the onset of labour?
-pulmonary surfactant
-increase of production of fetal cortisol stimulates an increase in maternal estriol
-increase in myometrial oxytocin
what causes cervical softening
increase in hyaluronic acid will decrease bridging among collagen fibres, decreasing firmness of the cervix
what causes cervical ripening
changes include a decrease in collagen fibre alignment and strength, decrease in tensile strenght of the cervical matrix, and an increase in cervical decorin
what are the two parts of the first stage of labour called
latent phase
active phase
what happens in the latent phase
mild irregular uterine contractions, cervix shortens and softens, duration variable
-may last a few days
what happens during active phase
- 4cms onwards to full dilatation
- Slow decent of the presenting part
- Contractions progressviely become more rhythmic and stronger
- Normal progress is assessed at 1-2cms per hour
what is second stage of labour
complete dilatation of the cervix fully dilated to delivery of the baby
normal length of 2nd stage in nulliparous women
-under 3 hours with regional analgesia
-under 2 hours without
normal length of second stage in multiparous women
-under 2 hours with regional analgesia
-under 1 hour without
what is the third stage
delivery of the baby to expulsion of the placenta and fetal membranes
-about 10 mins
active management of third stage
use of oxytocic drugs
-controlled cord traction
what causes contractions
uterine muscle and pacemaker (region of tubal ostia, wave spreads in downward direction)
which one of these pelvises are preferred for labour
gynaecoid
what are the 7 cardinal movements of labour
-engagement
-descent
-flexion
-internal rotation
-crowning and extension
-restitution and external rotation
-expulsion
what is engagement
when 3/5ish of more of babys head is below pelvic inlet
what is descent
baby moves down through pelvis
what is flexion
baby puts chin to chest
-happens passively
what is internal rotation
rotation to anterior position
-babys looking at the spine
what is crowning and extension
when the head starts to come out of the vaginal ring
-very painful for the mother
-episiotomy may be require to prevent trauma at this point
what is restitution and external rotation
the return of the fetal head to the correct anatomic position in relation to the fetal torso
-so the shoulders can get out, turn the baby on its side
