Onset and management of parturition

Question 1

Define parturition

Answer 1

Process of giving birth

Question 2

Stages of labour

Answer 2

0 (latent phase) - irreg contraction, effacement and dilation of cervix
stage 1 - reg contract, effacement and full dilation
stage 2 - full dilation to birth
stage 3 - birth to expulsion of placenta and membranes

Question 3

Key pathways

Answer 3

• activation of myometrium
• action of placental steroids
• action of PGs and inflam
• action of oxytocin
• positive biofb mech

Question 4

Myometrial quiescence

Answer 4

During preg - prolif and hypertrophy of smt muscle of uterus
Capacity for contractility decreases

Question 5

How does capacity for contractility decrease?

Answer 5

hCG - inhib form of MGJ
Prog - inhib oest (forms MGJ)
CRH
Relaxin - relaxes smooth muscle 
Oxytocin - stim synth of relaxing PGs
Melatonin - suppresses myo oxytocin R

Question 6

Activation of myometrium

Answer 6

Uterine stretch and activation
Increase in oxytocin R at term
MGJ allow rapid propag of AP (stim by melatonin, oest and PGs) (inhib by prog, hCG and relaxin)
High conc of MGJ in fundus - more AP
MGJ synch myo responsiveness to neuroendo and intrauterine oxytocin system

Question 7

What does CRH do?

Answer 7

May stim PG product and respond to PGE2 and oxytocin

Question 8

Activation of fetal HPA

Answer 8

Increase cortisol from fetal adrenal gland
Acts on placenta - decrease placental oest and prog
Increase stim PGs from uterus between layers of fetal membranes

Question 9

Prostaglandins

Answer 9

Increase conc during labour
Synth by uterine tissue and fetal membranes
Inhib PGs - delay labour
Give PGs - induce labour

Question 10

Inflammatory uterocervical processes

Answer 10

Progressive release of inflam mediators toward latter part of pregnancy

• Cytokines: stim PG synth
• Interleukins: increase collagenolytic activity of cervix
• NO: stim release of PGE2 from fetal mem

Question 11

What happens during cervical ripening and dilation?

Answer 11

Major altering of ECM and cellular comp

Question 12

Prog vs Oest during preg/labour

Answer 12

DRAW

Question 13

Oxytocin

Answer 13

Prod by supraoptic nuc and paravent nuc
Modulated by progesterone
Late preg - increase in oxytocin R
Released in labour - f.b. to brainstem

Question 14

Oxytocinase

Answer 14

Rapid deg of oxy - stops desensitisation

Question 15

How to fetal neurons help prep for delivery?

Answer 15

Mat oxy reaches fetal brain, GABA switch to inhib in fetal cortical neurons
Silences fetal brain during delivery - decrease hypoxic damage

Question 16

Labour

Answer 16

Involuntary
Fundal dominance
Contraction and retraction of uterine muscle fibres

Question 17

Effacement

Answer 17

Shortening of cervix

Question 18

Second stage of labour (birth of baby)

Answer 18

1. Contractions - longer and stronger but less frequent
2. Secondary power (the passage) - pressure creates urge to push
3. Fetal axis pressure - fetus displaces soft tissue in pelvis