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Week 16: Pregnancy > Physiology of Labour > Flashcards

Flashcards in Physiology of Labour Deck (26)
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1

Uterotropins (function and 4 examples)

Set the stage for contractions and cervical change (ripen the cervix)
Ex: estrogen, relaxin, Ca dependent phospholipases, arachidonic acid (to make prostaglandins)

2

What hormone counteracts uterotropins?

Progesterone
Maintains uterine quiescence
Decreased progesterone is involved in cervical ripening

3

Uterotonins (function and 3 examples)

Directly involved in contraction of myometrial smooth muscle cells
Increase intracellular Ca in myometrium
Ex: oxytocin, prostaglandins (PGF2a), endothelin 1

4

Do we know what initiates parturition in humans?

Nope!

5

Where are prostaglandins produced?

Interface of the amnion/chorion and myometrium

6

Does progesterone activate or inhibit prostaglandin production?

Inhibit
Increases progesterone increases the amount of prostaglandin dehydrogenase

7

PGE2 function

Cervical effacement
Highest levels of PGE2 are in amniotic fluid just below the presenting forewaters
Cause the breakdown of the rigid structure of collagen fibers (unwinds the fibers)
Softens the ECM

8

How is PGF2a produced? What is its function?

The thinning of lower uterine segment during active labour causes an inflammatory response, which results in the release of arachidonic acid
This process is also stimulated by oxytocin
PGF2a causes an increase in intracellular Ca (and contraction)

9

Oxytocin receptors
1. When do they increase
2. What are they increased by
3. What are they down regulated by

1. Near term
2. Estradiol
3. Progesterone

10

What does oxytocin do?

Increases the amount of intracellular Ca, which helps with contraction

11

How are gap junctions in the myometrium affected by
1. Estradiol
2. Progesterone

1. Increased
2. Decreased

12

5 ways to induce labour

Amniotomy (artificially rupture the membranes)
Membrane sweeping
Prostaglandins
Foley catheter in cervix
Oxytocin

13

3 meds to give to prevent labour

NSAIDs (but only for 2 days because dont want to close PDA)
Progesterone
Ca channel blockers

14

Definition of labour

Progressive cervical dilation, effacement, or both, resulting from regular uterine contractions every 5 mins lasting 30-60s

15

First stage of delivery

Onset of involuntary painful regular contractions to full dilation
Has latent and active phase

16

Latent phase

Onset of regular painful contractions every 5 mins lasting 30-60 s
Cervix is less than 3 cm dilated
Extremely variable duration

17

Active phase

Regular painful contractions every 2-3 mins lasting 45-60s
Cervix 3-4cm to fully dilated
A bit faster in women who had more than one pregnancy

18

Second stage of delivery

Full cervical dilation to the delivery of fetus
Maternal pushing increases forces directing fetus downwards and outwards

19

Third stage of delivery

Delivery of baby to delivery of placenta
Can take 0-30 mins (most deliver by 15 mins)

20

4 signs of placental separation

Gush of blood
Lengthening of cord
Fundus rises up
Uterus becomes firm and globular

21

3 ways to reduce the risk of postpartum hemorrhage in the third stage

Give uterotonics with delivery (oxytocin, misoprostol)
Gentle, controlled cord traction
Maybe early cord clamping

22

Fourth stage

The 1-1.5 hours after the delivery of placenta
Bleeding slows
Uterus remains contracted
Maternal stabilization and bonding
First attempt at breastfeeding

23

Puerperium phase

6 weeks following delivery
Most physiological changes return to non-pregnant state
Uterine bleeding stops by contraction of muscle around vessels and thrombus formation
Involution of uterus (gradual)
Cervix lengthens
Diuresis of increased circulatory volume

24

How does milk produced after the delivery of the placenta?

Delivery of placenta
Decrease in the amount of estrogen and progesterone
Increase in prolactin from anterior pituitary
Milk production

25

Suckling stimulates what hormone?

Oxytocin
Causes myoepithelial cells around alveoli in breast glands contract
Milk ejected

26

A decrease in what hormone causes menses to resume?

Prolactin