normal birth

Question 1

define parturition

Answer 1

the process of giving birth

• expelling the fetus, placenta and membranes from the uterus

Question 2

challenges in human parturition

Answer 2

Quiescence - of uterus with growth, distension, pressure

timing - for safe birth

activation - stimulation of uterine musculature changes in genital tract

birth - fetal-neonatal adaptations

involution - haemostasis, establishing lactation

Question 3

physiological processes

Answer 3

1. quiescence
2. activation
3. stimulation
4. involution

Question 4

anatomical changes leading to pregnancy

Answer 4

uterus - upper and lower segments

cervical changes = ripening

softening shortening effacement

membrane rapture

Question 5

uterine quiescence

Answer 5

uterine muscle contractions poorly synchronised

low amplitude and frequency

painless

cervix remains firm and closed

hormone responsible = P4 (form corpus luteum and placenta)

Question 6

mifepristone

Answer 6

drugs which blocks P4 a and b

can be used to induce labour later on in pregnancy

(progesterone is normally a muscle relaxant)

Question 7

factors that may determine gestation length

Answer 7

• parity
• age
• genetics-maternal and paternal
• race-ethnicity

Question 8

activation

Answer 8

timing - 37-42 weeks

activation involves fetal genome

• uterine stretch-growth (twins earlier)
• fetal HPA axis
• membrane ruptures
• upregulation of myometrium

Question 9

activation: up-regulation of myometrium in labour

Answer 9

increased PG receptors
increased oxytoxin receptors
increase in CAPS (gap junctions connexin 43)

Question 10

contraction associated proteins

Answer 10

increase myometrial contractility
= actin myosin

increase myocyte excitability ion channels
= Ca2+ voltage, regulated

increase intercellular connectivity gap junctions
= connexin 43

Question 11

PGs and labour

Answer 11

final stage of labour is an inflammatory event through PG

- potent inducer of labour

Question 12

action of PG in labour

Answer 12

increase myometrial contractility

lead to cervix changes

associated with membrane rupture

Question 13

cervical ripening

Answer 13

firm hard cervix gets remodelled by numerous cytokines causing extracellular matrix to breakdown and soften. leads to opening of the cervix

Question 14

cervical ripening

Answer 14

firm hard cervix gets remodelled by numerous cytokines causing extracellular matrix to breakdown and soften. Leads to opening of the cervix

can happen preterm = infection

term = P4 decrease, E2 increase

Question 15

membranes

Answer 15

amnion and chorion

• site of PG production
• rupture not essential for labour
• method of inducing labour

Question 16

major changes to the uterus during parturition and success for labour

Answer 16

• increased coupling
• increased ion channels
• increased receptors
• decreased NO

causes

• increased conductivity and excitability
• decreased relaxation

=reinforcement of contractions

Question 17

major changes to the cervix during parturition and success for labour

Answer 17

• increased inflammatory response
• increased collagenolysis

causes
- increased ripening

= dilatation

Question 18

major changes to the fetal membranes during parturition and success for labour

Answer 18

• increased ECM degradation

causes
- decreased tissue integrity

= rupture

Question 19

stages of labour

Answer 19

1st = until full dilatation (10cms)

2nd = full dilatation until birth of baby

3rd = from birth of baby until delivery of the placenta

Question 20

partogram

Answer 20

graphical description of labour

• looks at progress of labour
• women having first baby have a slower labour than 2nd +
• time against cervical dilatation

Question 21

1st stage of labour

Answer 21

contractions

cervical effacement and dilatation

descent of presenting part

intrauterine pressure increases (about 25mmHg pain felt)

Question 22

CVS adaptation in neonate

Answer 22

• closure of foramen ovale
• 100% of right ventricle CO has to go through lungs therefore needs to be a rapid reduction in pulmonary vascular resistance (to allow blood to go through lungs)
• reduction-closure ductus aretiosus (pulmonary to aorta)

Question 23

things needing to happen at birth

Answer 23

establishing continuous breathing

thermogenesis

intermittent nutrition

cardiovascular adaptations

Question 24

involution

Answer 24

• placental seperation
• cleavage through decidua basalis
• contractions to prevent postpartum haemorrhage
• increased uterine sensitivity to oxytocin

Question 25

P4 effect of labour

Answer 25

pregnancy hormones such as P4 put the brakes on myometrium

Question 26

normal term labour

Answer 26

- inflammatory response - multiple steps in a cascade - requires interplay between fetoplacental unit and myometrium