Normal birth

Question 1

What is parturition

Answer 1

Getting the baby foetus from the uterus to the outside world via changes of the cervix and uterus.

Question 2

Physiological processes in parturition.

Answer 2

Quiescence
Activation
Stimulation
Involution

Question 3

What is quiesence, what causes it?

Answer 3

Pain less, unsynchronised uterine contractions stimulated by PG2.

Question 4

What is thought to trigger labour?

Answer 4

FUNCTIONAL withdrawal of PG (decrease PG-A and PG-B receptors fucntion) which decreases E:PG ratio allowing for other sm stimulants such as oxyctocin to induce labour.

Question 5

Factors determining gestation length.

Answer 5

Parity
Age
Genetics
Ethnicity

Question 6

How does PG work?

Answer 6

Reduces prostaglandin-F synthesis which induces oxytocin (sm stimulant) release.

Affects Ca2+

Affects Beta-adronergic receptors.

Question 7

Mifepristone

Answer 7

PG receptor antagonist, used to induce labour or in abortions.

Question 8

Impact of being human on gestation length

Answer 8

Stress! - Increased in acute phase proteins (CRP, TNF-a) etc. in sustained and high stress environments could reduce gestational length.

Question 9

What does activation of parturition involve?

Answer 9

Foetal genome
Uterine-stretch - Twins, more stretch, more uterus wants to contract
Upregulation of myometrium via - Gap junctions, Prostaglandins, and oxytocin.

Question 10

Drugs that inhibit labour for preterm births

Answer 10

Ca2+ blockers inhibit myometrial contractility/excitability

e.g Nifedipine

Question 11

What is the triad of processes that occur upon labour induction?

Answer 11

1. Myometrial contractility
2. Cervix ripening
3. Membrane rupture association

Question 12

Three things that up-regulate myometrial activity

Answer 12

1. Inc. in gap junctions allowing for more fast and synchronous AP propagation
2. Release of oxytocin from post. pit. which induces smooth muscle uterine contractions. Not very good at initiation of labour
3. Prostaglandin release which is the most potent inducer of labour. Can be used for abortions as well

Question 13

Stages of birth

Answer 13

1. First stage
   - From initiation of labour to full dilation (10cm)
2. 2nd stage
   - Full dilation to birth
3. 3rd stage
   - Birth to placenta delivery

Question 14

Stages of labour

Answer 14

Latent phase

• Cervical ripening
• Presenting part of baby descends down to pelvis

First stage/active stage

• Real labour commences and full contractions
• Cervical enfacement and dilation until full dilation
• Membranes rupture

Second stage
- Full dilation till delivery of baby

Third stage
- From birth of baby until completion of placental delivery

Question 15

What is needed after birth

Answer 15

1. Ensure continuous breathing as foramen ovale needs to close and theres high pulmonary vascular resistance.
2. Thermogenesis- Baby has high vascularised brown fat which maintains body temperature, dry baby off to prevent evaporative heat loss.
3. Intermittent nutrition
   - Initiates lactation
   - Induces uterus contraction to prevent bleeding
   - Eye-eye bonding

Question 16

What is stimulation

Answer 16

Active labour thought to birth of the baby

Question 17

Involution

Answer 17

Placental delivery
It is cleaved through decidua basalis
Uterus is more sensitive to oxytocin which contracts uterus preventing a bleed out.