Intra/post - Normal labour and birth

Question 1

mechanisms of labour definition (also known as cardinal movements of labour)

Answer 1

the series of changes in position and attitude which the foetus undergoes during its passage through the birth canal

Question 2

what are the different mechanisms involved in labour

Answer 2

engagement
descent
flexion
internal rotation
extension
restitution and external rotation
expulsion

Question 3

what occurs during engagement

Answer 3

the foetus nestles into the pelvis - also known as “dropping” or “lightening”

the foetus is engaged when the biparietal diameter of the foetal head reaches the level of the maternal ischial spines - below the plane of the pelvic inlet

Question 4

what occurs during descent

Answer 4

the uterus contracts and pushes the baby down the birth canal - foetal head descends through the pelvic brim to the mid cavity

Question 5

what occurs during flexion

Answer 5

flexion is a passive flexion of the head that permits the smallest diameter of the fetal head (suboccipitobregmatic diameter) to be presented to the maternal pelvis

passive because uterine activity is fundally dominant; the line of force is down the fetal spine and causes flexion of the fetal head

Question 6

what occurs during internal rotation

Answer 6

the whole foetus internally rotates until its facing the maternal back with head at level of the ischial spines

Question 7

what occurs during extension

Answer 7

As the head continues its descent, gradual extension of the foetal head around the pubic symphysis occurs - distends the perineum

with more extension the widest diameter passes through the vulval introitus (crowning) and the head is born by extension at the neck

Question 8

what occurs during restitution and external rotation

Answer 8

after the head is born, the shoulders enter the maximum diameter of the maternal pelvic inlet

as they descend through the canal, the shoulders rotate (just as the head did in internal rotation) - as they do so the head (outside the body) rotates back to its original position but now with shoulders anterior/posterior - comes out sideways

Question 9

what occurs during expulsion

Answer 9

essentially delivery of the baby

• delivery of the anterior shoulder is aided by gentle downward traction on head
• the posterior shoulder is then delivered by gentle upward traction on the head
• following these maneuvers the body, legs, and feet are delivered with gentle traction on the shoulders