Labour

Question 1

How many weeks of gestation is defined as “term”?

Answer 1

37-41

Question 2

Recall the boundaries of “pre-term” and “very pre-term” delivery

Answer 2

22-37 weeks

very preterm- 22-28

Question 3

Recall the factors moderating the cervical changes that occur in labour

Answer 3

PGE2
IL8
MMPs

Question 4

Recall the factors moderating the endometrial changes that occur in labour

Answer 4

PGE2

Oxytocin receptor upregulation

Question 5

Where is PGE2 produced in labour?

Answer 5

Foetal membranes

Question 6

Describe the changes in the foetal membranes during labour?

Answer 6

Inflammatory process occur, and the FMs secrete PGs, ILs and MMPs

Question 7

Summarise the endocrine and biochemical promotors of labour

Answer 7

Promotors of labour requires pro-inflammatory factors.
Key regulators: CRH, PAF, Progesterone and NFKB. (CRH, PAF and NFKB are proinflammatory and pro-labour, progesterone is anti-labour)
CRH and PAF upregulate pro-inflammatory cytokines
NFKB is the key TERM labour initiator but is normally inhibited by progesterone. Progesterone loses its anti-labour effects at term and this allows NFKB to initiate labour

Question 8

Summarise how progesterone loses its anti-labour effects at term

Answer 8

Presence of progesterone/PR = proinflammatory genes will be switched off because the Progesterone-PR complex inhibits the transcription factor NFKB which normally transcribes these proinflammatory proteins.

During normal TERM labour:
functional progesterone withdrawal (slide 65) leads to increased NFKB activity= activation of proinflammatory genes= labour

Question 9

What is the role of NFKB in labour?

Answer 9

Involved in pro-inflammatory processes, upregulates proinflammatory genes including cytokines, MMPs, oxytocin receptors

Question 10

Describe the epithelial changes in the foetal membranes during labout

Answer 10

Amnion epithelium on BM loses strength

Question 11

What 2 processes are undergone by the cervix in labour?

Answer 11

Effacement and dilatation

Question 12

What is cervical effacement?

Answer 12

Cervix becoming softer, thinner and more flexible

Question 13

What must happen in order for cervical effacement to occur?

Answer 13

Excessive ECM remodelling

Question 14

Recall the key mediators in uterine contraction in labour

Answer 14

PGE2 from foetal membranes

Oxytocin receptor

Question 15

How long does the onset of uterine contraction last in labour?

Answer 15

About 8 hours

Question 16

When do foetal membranes usually rupture?

Answer 16

During onset of labour

Question 17

What is the 2nd stage of uterine contraction, and how long does it last?

Answer 17

Expulsive effort

About 30 mins

Question 18

Name the 3 stages of labour

Answer 18

1. Cervical ripening and effacement and onset of myometrial contraction
2. Delivery of infant
3. Delivery of placenta

Question 19

How long should the 3rd stage of labour last?

Answer 19

30 minutes

Question 20

Summarise the non-haematological events of the 3rd stage of labour

Answer 20

Uterus contracts very powerfully to expel the placenta, causing a rupture between the uterus service and the placenta –> delivery

Question 21

What conditions are required in the spiral arteries in order to achieve successful haemostasis in placental delivery

Answer 21

High flow and low pressure

Question 22

How does the myometrium control haemostasis following placental delivery?

Answer 22

Contracts forecefully

Question 23

What is involution and what drives it?

Answer 23

The powerful myometrial contraction that causes haemostasis of spiral arteries
Driven by oxytocin (contractile hormone)

Question 24

Summarise the hypothesis for parturition

Answer 24

CRH increase
Foetal adrenal stimulated
Positive feedback in lacenta between CRH and cortisol
Cortisol drives IL, PG and PAF production = pro-labour factors