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Reproduction > Physiology of pregnancy > Flashcards

Physiology of pregnancy Flashcards

1
Q

Describe role of placenta

A
  • Fetal and maternal blood is separated by a layer of tissue allowing 2 way exchange
  • serves as a temporary endocrine organ
  • placenta and fetal heart functional at 5weeks
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2
Q

Describe circulation in the intervillous space from mother to baby

A

= acts as an arteriovenous shunt from mother to baby

  • blood spurts out into pools in decidua from maternal arterial circulation
  • it then returns to bloodstream through venous system draining into uterine veins
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3
Q

How is oxygen supply to the fetus facilitated? (3 factors)

A
  • Fetal Hb has an increased ability to carry oxygen
  • High Hb conc. in fetal blood
  • Bohr effect: fetal Hb can hold on to oxygen better at lower P02 levels
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4
Q

Describe the role of HCG throughout pregnancy

A

rises until about 10 weeks then falls

  • prevents involution corpus luteum
  • effects on testes male fetus
  • causes morning sickness
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5
Q

Describe the role and release of human chorionic somatomammatropin thoughout pregnancy?

A

Rises throughout pregnancy

  • produced from wk 5
  • growth hormone-like effects = protein tissue formation
  • decreases insulin sensitivity for mother = more glucose for fetus
  • involved in breast development and possibly lactation
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6
Q

Describe the role of progesterone throughout pregnancy?

A
  • development decidual cells
  • decreases uterine contractions
  • preparation for lactation
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7
Q

Describe the role of estrogens thoughout pregnancy

A
  • enlargement uterus
  • breast development
  • relaxation ligaments
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8
Q

What hormones are released from the placenta? what can these cause in the mother?

A

CRH:
-causes release ACTH in mother
-aldosterone and cortisol released
=HTN, oedema, insulin resistance, gestational diabetes

HCG/HC thyrotropin:
-causes hyperthyroidism in mother

Increase in calcium demands:
-hyperparathyroidism in mother

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9
Q

Cardiovascular changes in pregnancy:

  • what happens to CO
  • what happens to HR
  • what happens to BP
A

CO:

  • raises 30-50% above normal
  • decreases in last 8wks
  • increases 30% during labour

HR:
-increases up to 90/min

BP:
-drops during second trimester as peripheral resistance decreases and uteroplacental circ. expands

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10
Q

Haematologic changes in pregnancy:

  • plasma volume
  • erythropoeisis
  • Hb
  • iron requirements
A
  • Plasma volume increases proportionally with CO
  • erythropoeisis increases 25%
  • Hb decreases due to dilution
  • iron requirement increases (supplement)
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11
Q

Respiratory changes during pregnancy:

  • resp. rate
  • tidal and minute volume
  • vital capacity
  • P02
A
  • Resp rate increases
  • tidal and minute vol. increases
  • vital cap. and p02 don’t change
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12
Q

Describe the changes to urinary system during pregnancy

  • GFR and renal plasma flow
  • reabsorption of ions and water
A

GFR and renal plasma flow increase

increase in reabsorption of ions and water due to placental steroids and aldosterone

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13
Q

What is the anabolic and catabolic phase of pregnancy?

A

Anabolic:

  • 1-20wks
  • growth breast/uterus/wt gain

Catabolic:

  • 21-40wks
  • high metabolic demands fetus, accelerated starvation mother
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14
Q

What specific nutritional supplements are needed in pregnancy?

A

High protein diet, high energy intake

  • iron supplements = 300mg ferrous sulphate
  • B vitamins = erythropoeisis
  • Folic acid = neural tube defects
  • Vitamin D3 and calcium
  • before parturition K vitamin = prevention intracranial bleed during labour
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15
Q

Describe the hormones involved and the mechanisms of the onset of labour

  • estrogen affect
  • ocytocin and prostaglandin affect
  • baxton-hicks contactions
  • neurogenic reflex
  • fergusons reflex
A

Estrogen from uterus: increases uterine contractility, induces oxytocin receptors in uterus

Oxytocin from fetus and posterior pituitary of mother stimulates uterine contraction, stimulates placenta to release prostaglandin which stimulates more vigorous contractions which stimulates placenta to release prostaglandins (+ve feedback)

  • oxytocin is the strongest stimulator for uterine contractions
  • prostaglandins stimulate cervical ripening and stimulate myometrial contractions

Baxton-hicks contractions: fetal head stretched cervix and increases contractility which causes more stretching

Strong uterine contractions and pain from birth canal = neurogenic reflex from spinal cord for intense abdominal muscle contractions

Fergusons reflex:
-pressure applied to internal end cervix causes oxytocin to be released increasing uterine contractions causing more pressure (+ve feedback)

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16
Q

Describe the physiology of lactation

A

Estrogen = growth of ductile system
Progesterone = development of lobule-alveolar system
-both of these inhibit milk production and theres a drop in these at birth

Prolactin stimulates milk production (steady rise from wk5 to birth)
=stimulates clostrium

17
Q

What is the milk let down reflex?

A

Receptors in nipple stimulated

Impulses propogated to spinal cord

stimulation hypothalamic nuclei

oxytocin release from post. pituitary

milk expelled due to smooth muscle contraction and milk is let down from mammary gland

18
Q

Describe milk production association with childs cry

A

childs cry
-causes higher brain centres to decrease PIH (prolactin inhibiting hormone)
-inhibition prolactin cells in ant. pit. removeed
=increase prolactin
=milk secretion

19
Q

What are the 3 key factors of labour?

A

Power: uterine contractions
Passage: maternal pelvis
Passenger: fetus

20
Q

What are the three stages of labour?

A

1st stage = cervical dilation
2nd stage = passage through birth canal
3rd stage = expulsion placenta

21
Q

Describe the 1st stage labour

A

Latent phase:

  • up to 3-4cm dilation
  • mild irregular contractions
  • duration variable (days)

Active phase:

  • 5-10 cms dilation
  • slow descent presenting part
  • contractions more rhythmic and stronger
22
Q

Describe the second stage labour?

A

10cm dilated to delivery

  • nulliparous woman = 3hrs with regional anaesthesia, 2hrs without
  • multiparous woman = 2hrs with, 1hr without
  • if longer than this = prolonged
23
Q

Describe the third stage of labour

A

delivery baby to expulsion placenta and membranes

  • av duration 10mins but can be 3mins or longer
  • if longer than 1 hour prepare to remove under GA

Expectant management: spontaneous delivery
Active management: lowering risk post-partum haemorrhage

24
Q

Describe what is included in active management of the third stage of labour

A
  • Prophylactic admin oxytocin 10units
  • Ergometrine 1ml
  • Cord clamping and cutting
  • Controlled cord traction
  • Bladder emptying
  • injection oxytocin directly into cord (rarely works)
25
Q

Describe the cervical changes in labour

A

Softening
Effacement (shortening)
Dilation

26
Q

Baxton-hicks contractions:

  • what is the nature of these contractions
  • will these lead to delivery
A

‘False-labour’

  • painless, irregular contractions that don’t increase in frequency or intensity
  • won’t lead to delivery soley
  • felt in 2nd and 3rd trimester
27
Q

True labour contractions:

  • describe the nature
  • how frequent are these
  • how do they progress
A

Wave like pain, builds to a peak then ebbs away

Pacemaker:

  • regions of tubal ostia, wave spreads in downward direction
  • synchronisation of contractions from both ostia

Polarity:

  • upper segment contracts and retracts
  • cervix/lower segments relaxes and dilates

Intensity:

  • degree of uterine systole - grades mild/mod/strong
  • severe in 2nd stage

Frequency:
-normal is up to 3-4 in 10mins, allows time for resting tone

Duration:
-initially 10-15s, max 45s - slowly builds

28
Q

Which types of pelvis exist?

A

Gynacoid - most suitable female pelvis shape

Anthropoid - • There is an oval shaped inlet with large anterio-posterior diameter and comparatively smaller transverse diameter

Android:
• Android shaped pelvis has triangular or heart-shaped inlet and is narrower from the front. African-Caribbean women are more at risk of having an android shaped pelvis

29
Q

rupture of membranes:

  • when can this take place?
  • what is the function of liquor?
A

¥ Liquor: nurtures and protects fetus and facilitates movement

¥ Timing of rupture
¥ Pre-Term
¥ Pre-Labour – this can be days (wear a pad)
¥ First Stage
¥ Second Stage
¥ Born in a caul – born in all the membranes

30
Q

Describe the normal fetal position:

  • lie
  • presentation
  • presenting part
  • position
A

¥ Longitudinal Lie

¥ Cephalic Presentation

¥ Presenting part: Vertex

¥ Position: Occipito-anterior; head engages occipito-transverse

¥ Flexed Head

31
Q

Describe the mechanism of labour

A 
¥	Engagement 
¥	Decent
¥	Flexion
¥	Internal Rotation
¥	Crowning and extension
¥	Restitution and external rotation (head adopts optimal position for shoulder)
¥	Expulsion, anterior shoulder first
32
Q

What is the bishop score?

-what is it used for?

A

¥ The Bishop score and it variations is used widely
¥ Its advantage lies in its simplicity, reproducibility, and predictability in successful inductions.
¥ Equal weight is given to each of the five elements,
1. Position
2. Consistency
3. Effacement
4. Dilatation
5. Station in Pelvis (in fifths)

Bishop score remains the best and simplest method available to determine if it is safe to induce labour.

33
Q

What is normal blood loss in labour, how is haemostasis achieved?

A

<500mls

Haemostasis is achieved by:

  • tonic contraction = strangulates blood vessels
  • thrombosis of torn vessel ends = hypercoag. state
  • myo-tamponade = opposition of anterior/posterior walls
34
Q

Describe how the placenta separates?

A

Shearing force: inelastic placenta opposed with a decreasing surface area of placental bed which has contracted

  • uterus contracts and rises
  • umbilical cord lengthens permenently
  • gush blood
35
Q

How long does it take for tissues to return to normal puerperium?

A

6wks

36
Q

Describe the different lochia seen postpartum?

A

Lochia rubra = red - 1-3 days postpartum

Lochia serosa = pink - 3-10 days

lochia alba = white - 10-14 days, may last 6wks

Reproduction (34 decks)

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