Physiology of labour

Question 1

Define parturition

Answer 1

Labour and childbirth

Question 2

What is meant by placental clock?

Answer 2

Predestined lifespan of placenta is up to 42 weeks. After this, reduced release of progesterone from placenta and function decreases

Question 3

What is meant by the foetal clock?

Answer 3

Baby starts producing oestrogen therefore baby is main decided of when labour begins. Oestrogen produced by adrenal glands in the foetus

Question 4

Easy way to remember if prostaglandin dilates or contracts?

Answer 4

Vowel= dilator
Consonant= contractor

Question 5

What prostaglandins do oestrogens predominantly make?

Answer 5

F and C (contractor)

Question 6

What prostaglandings do progesterones predominantly make?

Answer 6

E and I (dilators)

Question 7

What is cervical ripening?

Answer 7

Cervix changes from cylinder to small circle
Becomes soft and pliable
Mediated by collagenolysis

Question 8

What is myometrial ripening?

Answer 8

Increased cell to cell adhesion and more production of gap junctions
Causes increased oxytocin receptor expression at fundus

Question 9

What is the main drive for myometrial ripening

Answer 9

Oxytocin

Prostaglandins enhance this change

Question 10

What is Ferguson’s reflex?

Answer 10

Oxytocin release in circulation, arrives at fundus
Triggers myometrial contraction
Cranial–> caudal contraction, baby pushed further into cervix
Stretch of cervix causes further increase in oxytocin so more contractions

Question 11

3 signs of labour

Answer 11

Membrane rupture
The show- release of mucus plug which seals cervix
Painful contractions (lasting >40 seconds and come closer and closer)

Question 12

What is the danger of a baby that doesn’t deliver 24 hours after membrane rupture

Answer 12

Bacterial infection

Question 13

Why is backache a symptoms of labour?

Answer 13

Innervation of cervix comes from S3-S4 so stimulates nerve endings in the back

Question 14

What happens in the first stage of labour?

Answer 14

Cervix effaced and dilates from 0-10cm
Myometrial fibres contract and retract
Upper segment of uterus becomes heaped up whilst lower part passivelt thins

Question 15

How is first stage of labour divided?

Answer 15

Latent phase: 1-3cm dilation

Active phase: 3-10cm dilation

Question 16

How quick should dilation occur?

Answer 16

First time mum: 1-3cm per hour

Second etc time mum: 3-6cm per hour

Question 17

What happens during the second stage of labour?

Answer 17

Uterus and vagina form a continuous tube
Uterine contractions supplemented by voluntary contractions of diaphragm
Pelvic floor muscles stretched backwards

Question 18

How long should second stage of labour take?

Answer 18

40 mins in first time mum

20 mins otherwise

Question 19

2 phases of the second stage of labour?

Answer 19

Propulsive phase: from full dilation to presenting part reaching pelvic floor
Expulsive phase: reaching pelvic floor to delivery

Question 20

What happens during the third stage of labour?

Answer 20

Uterine muscles contract tonically to constrict blood vessels passing between interlacing fibres
Placenta separates as placental bed is constricted to half size and expelled from uterine

Question 21

How long should third stage of pregnancy take

Answer 21

30 mins: otherwise expect severe haemorrhage

Question 22

3 factors that affect progression of labour?

Answer 22

The passenger
The passage
The powers

Question 23

How is babies skull adapted for labour?

Answer 23

Skull bones held by fontanelle, allowing bones to override eachother which reduces dimension of babies head

Question 24

What is the curve of carus

Answer 24

Passage baby has to follow

Question 25

What is the best position for labour

Answer 25

Squatting

Question 26

What is the course of action of mothers pelvis is less than 10 cm

Answer 26

C section

Question 27

What is platypelloid?

Answer 27

African pelvis
Kidney shaped pelvis causes difficulty is labourn ending in obstructive pregnancies
Can result in fistula

Question 28

What is shoulder dystocia

Answer 28

Shoulder becomes stucks- 3 minutes before brain damage begins

Question 29

Function of partogram

Answer 29

Tracks womens progress in labour

Question 30

Episiotomy

Answer 30

Cuts through vaginal epithelium, perineal skin, bulbocavernosus muscle, superficial and deep muscles