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Flashcards in normal birth Deck (26):
1

define parturition

the process of giving birth

- expelling the fetus, placenta and membranes from the uterus

2

challenges in human parturition

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

3

physiological processes

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

4

anatomical changes leading to pregnancy

uterus - upper and lower segments

cervical changes = ripening

softening shortening effacement

membrane rapture

5

uterine quiescence

uterine muscle contractions poorly synchronised

low amplitude and frequency

painless

cervix remains firm and closed

hormone responsible = P4 (form corpus luteum and placenta)

6

mifepristone

drugs which blocks P4 a and b

can be used to induce labour later on in pregnancy

(progesterone is normally a muscle relaxant)

7

factors that may determine gestation length

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

8

activation

timing - 37-42 weeks

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

9

activation: up-regulation of myometrium in labour

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

10

contraction associated proteins

increase myometrial contractility
= actin myosin

increase myocyte excitability ion channels
= Ca2+ voltage, regulated

increase intercellular connectivity gap junctions
= connexin 43

11

PGs and labour

final stage of labour is an inflammatory event through PG
- potent inducer of labour

12

action of PG in labour

increase myometrial contractility

lead to cervix changes

associated with membrane rupture

13

cervical ripening

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

14

cervical ripening

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

15

membranes

amnion and chorion

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

16

major changes to the uterus during parturition and success for labour

- increased coupling
- increased ion channels
- increased receptors
- decreased NO

causes
- increased conductivity and excitability
- decreased relaxation

=reinforcement of contractions

17

major changes to the cervix during parturition and success for labour

- increased inflammatory response
- increased collagenolysis

causes
- increased ripening

= dilatation

18

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

- increased ECM degradation

causes
- decreased tissue integrity

= rupture

19

stages of labour

1st = until full dilatation (10cms)

2nd = full dilatation until birth of baby

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

20

partogram

graphical description of labour

- looks at progress of labour

- women having first baby have a slower labour than 2nd +

- time against cervical dilatation

21

1st stage of labour

contractions

cervical effacement and dilatation

descent of presenting part

intrauterine pressure increases (about 25mmHg pain felt)

22

CVS adaptation in neonate

- 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)

23

things needing to happen at birth

establishing continuous breathing

thermogenesis

intermittent nutrition

cardiovascular adaptations

24

involution

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

25

P4 effect of labour

pregnancy hormones such as P4 put the brakes on myometrium

26

normal term labour

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