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Repro > Pregnancy, the placenta and birth > Flashcards

Pregnancy, the placenta and birth Flashcards

1
Q

When does the placenta first start to develop?

A

2nd week of development

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2
Q

How does the endometrium control the invasive force from the trophoblast

A

It undergoes a change to become the decidua

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3
Q

Describe the formation of the placenta (3 steps)

A
  1. finger like projections of trophoblast develop into the endometrium (primary villi)
  2. mesenchyme invades the projections (secondary villi)
  3. fetal vessels infiltrate the mesenchyme core (tertiary villi)
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4
Q

Describe the layers of cells between the mother and the baby at the placenta (5 layers)

A
  1. endometrium
  2. syncitiotrophoblast
  3. cytotrophoblast
  4. undifferentiated mesoderm
  5. fetal capillary mesoderm
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5
Q

The babies demands for gas and nutrient change increases as it grows, how does the placenta accomodate for this increase in demand?

A

The cytotrophoblast and mesoderm layers thin, meaning the overall barrier for diffusion thins as the baby grows, this makes gas exchange more efficient. The placenta will also grow and develop more villi to increase its SA

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6
Q

The placenta has many folds, each of which contain a main stem villus and its many branch villi. What are these folds called?

A

Cotyledon

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7
Q

Describe the circulation of blood at the placenta

A

Endometrium arteries from the mother open up at the syncitiotrophoblast and so bathe the foetal villus/ blood vessels in maternal blood. Nutrients are exchanged (eg O2 into foetal artery and CO2 released) and the deoxygenated blood exits the cotyledon and is carried away by endometrial veins.

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8
Q

What hormones are produced by the placenta and what effect do they have?

A
  • progesterone and oestrogen to maintain endometrial lining (enough produced to take over from corpus luteum by 11th week)
  • Human chorionic gonadotrophin (hCG) - cheers on corpus luteum to keep producing progesterone and oestrogen
  • Human chorionic somatomammotrophin (hPL)- important for metabolic changes in mumn
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9
Q

How are IgGs transported to the foetus at the placenta?

A

receptor mediated pinocytosis

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10
Q

Why do ectopic pregnancies lead to perforations?

A

Embyro implants in follopian tube, where there is no endometrium, therefor there is no differentiation into decidua, so the invasive force of the embryo is not controlled

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11
Q

What is placenta praevia? what is its consequence?

A

Where the foetus implants into the lower uterus, causing haemorrhage during labour/ delivery. Baby can usually be born but needs C section

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12
Q

In what period is the embryo/ foetus most sensitive to teratogens?

A

first 2 weeks of gestation- embryo will usually die

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13
Q

In what period is exposure to teratogens most likely to cause physical abnormalities?

A

The main embryonic period (weeks 3-9)- the heart, lips and limbs have finished by the end of this period, the eyes, ears, teeth, palate and genitalia have finished their most sensitive phase

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14
Q

What structures are venerable to teratogens towards the end of pregnancy?

A

The neural tube is sensitive all the way through pregnancy, with CNS defects still sensitive in the final 4 weeks. The external genitalia, teeth and eyes are also in their less sensitive period in the last 15 weeks

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15
Q

List 5 common teratogens which may be prescribed

A
  • tetracyline
  • isotetrion
  • warfarin
  • statins
  • anticonvulsants
  • NSAIDs
  • ACEi and angiotensin blockers
  • opiods
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16
Q

Give 3 non prescribed teratogens

A
  • alcohol
  • drugs such as cocaine, MD, cannabis
  • infections (TB, malaria, syphillis, varicella zosta)
  • also smoking has an effect on foetal circulation.
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17
Q

Give 7 hormonal changes which occur in pregnancy

A
  • progesterone increase from placenta
  • oestrogen increase from placenta
  • hCG from placenta
  • hPL from placenta
  • prolactin increase
  • PTH increase
  • cortisol and aldosterone increase
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18
Q

Why do mothers get reflux in pregnancy?

A
  • increase progesterone= increased smooth muscle relaxation= relaxation of lower oesphageal sphincter
  • also effect of baby pushing up on stomach
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19
Q

Why do mothers get constipation in pregnancy?

A
  • increase progesterone= increased smooth muscle relaxation= less peristalsis of smooth muscle in gut
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20
Q

What benefits does progesterone have in pregnancy? (3)

A
  • maintains endometrial lining
  • vasodilates so decreases TPR so blood pressure is the same even though blood volume expands and CO increases
  • stimulates appetitie in the first half on pregnancy for fat deposition and increases fat synthesis from glucose
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21
Q

Why do pregnant mothers get a stuffy nose?

A

Vasodilation in nostrils= more mucus secretions

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22
Q

What 3 affects does oestriol (type of oestrogen) production from the placenta have?

A
  • maintains endometrium
  • inhibits HPG so new follicles are not stimulated to develop
  • stimulates prolactin release
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23
Q

What affect does prolactin release have?

A

stimulates breast enlargement and milk production

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24
Q

What effect does PTH release have on pregnancy?

A

Increases Ca2+ mobilisation so baby has plenty for growth

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25
Q

What 3 metabolic changes occur in pregnancy and how?

A
  • decreased responsiveness to insulin (due to Progesterone, oestrogen and hPL), so more glucose for baby
  • blood glucose decreases as baby is using all the glucose
  • increased fat deposition in first half of pregnancy due to progesterone, which means more fatty acid and ketones can be produced later as a fuel supply for mother (baby is using the glucose)
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26
Q

Why does gestational diabetes occur?

A

hPL works too well so suppresses insulin too much

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27
Q

What happens blood volume and cardiac output and why?

A

Blood volume expands by about 50% due to creation of blood vessels in the uterus and aldosterone release. Cardiac output increases accordingly to pump this expanded volume.

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28
Q

Why do you get odema in pregnancy?

A

Progesterone causes vasodilation, which increases venous pressure. Venous pressure is further increased by the baby compressing the IVC.

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29
Q

Why do you get varicose veins and haemorrhoids in pregnancy?

A

increased venous pressure due to vasodilation and ICV compression

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30
Q

Why are pregnant mothers at thrombus risk?

A

Theyre less mobile, and also hormone changes make them hypercoagulable (partly due to oestrogen increase)

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31
Q

How are the babies increased demands for O2 met?

A

Progesterone makes central chemoreceptors more sensitive to CO2, so tidal volume (increases a lot) and respiratory rate increases (a bit) to increase O2 intake and CO2 expulsion

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32
Q

Why is RAAS activated in pregnancy?

A

Progesterone vasodilates afferent arteriole, and causes a 160% increase in GFR. This increases distal Cl- delivery, so body assumes salt overloaded so increases water reabsorbtion by activating RAAS

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33
Q

Why can mothers get urinary incontinance during pregnancy?

A
  • Stretching of pelvic floor muscles
  • Pressure on bladder form baby
  • progesterone relaxes EUS
34
Q

Why is anaemia common in pregnancy? What is pseudoanaemia?

A
  • The baby and expanding haematocrit uses lots of iron up so become iron deficient
  • pseudoanaemia is where blood volumes are expanding but haematocrit isnt expanding to match
35
Q

What is the result of anaemia, smoking, COPD and asthma in pregnancy?

A

Baby has less O2, so slow development and low birth weight

36
Q

Define: partuition

A

the transition from pregnant state to non pregnant state

37
Q

What is the difference between labour and delivery?

A

Labour is the overall process by which the foetus is expelled from the body, delivery is only the physical method of expulsion.

38
Q

What promotes labour?

A

prostaglandin release, this may be due to:
- surfactant protein A increase in baby
- progesterone droo
- fetal cortisol
- cervical stretching
Specific method of prostaglandin release we are unsure of

39
Q

Where are the prostaglandins which promote labour released from?

A

the decuida and myometium

40
Q

What increases myometrial excitability at the end of pregnancy? (3)

A

Mechanical stretching increasing the size of gap junctions between smooth muscle cells so making them more excitable. Also oestrogen remaining high when progesterone falls at the end of pregnancy. The unopposed oestrogen also increases oxytocin receptor number in myometrium.

41
Q

What causes contractions in pregnancy?

A

Oxytocin release, and prostaglandins

42
Q

What prevents oxytocin release throughout pregnancy?

A

Progesterone inhibits its action. At the end of pregnancy progesterone falls which is why it becomes able to have an effect.

43
Q

What is the Ferguson reflex?

A
  • Prostaglandins are released
  • stimulates contractions and also positively feedsback to increase more prostaglandin release
  • contractions cause oxytocin release from myometrium, which further increases prostaglandin release
44
Q

What is cervical ripening?

A

The process by which the cervix goes from a strong structure which keeps the baby in, to something it can get through.

45
Q

What triggers cervical ripening?

A

Prostaglandins and increasing levels of relaxin towards the end of pregnancy

46
Q

What changes occur during cervical ripening?

A
  • reduction in collagen
  • increase in GAGs
  • increase in hyaluronic acid
  • reduced aggregation of collagen fibres
  • cervix becomes soft and effaced
47
Q

What changes occur to the perineal body during pregnancy?

A

It thins and becomes a more membranous and transparent structure as the baby stretches the levator ani muscle, which in turn stretched the perineal body.

48
Q

What are the complications of perineal tears?

A

bleeding, pain, haematoma, infection, scarring, urinary and fecal incontinance and fistula formation

49
Q

Describe and define the first stage of labour

A

It is the interval between onset of labour and full dilation (10cm) of the cervix.
Contractions start which force the baby into the birth canal. The cervix slowly dilates and softens. This is the latent phase and can last a variable amount of time.
This is followed by the active phase- a fast rate of change and more regular contractions.

50
Q

What are 2 characteristics of myometrial contactions?

A
  • They contract but then dont fully relax, so that the fibres just get shorter and shorter (contraction and retraction). This reduces space but increases pressure in the uterus .
  • They also start from the top down, forcing the baby in the right direction.
51
Q

What two processes increase the rate and force of myometrial contraction?

A

Towards the end of pregnancy Ca2+ builds up which increases the force of contraction. Prostaglandins aid release of more Ca2+ per action potential which causes stronger contractions.
Oxytocin lowers the threshold for contractions (more frequent contractions)

52
Q

Breifly describe and define the 2nd stage of labour

A

It is the time between full dilation of the cervix and delivery.
The uterine contractions change to become expulsive, the baby descends through the birth canal and is delivered.
The passive phase is the descent and rotation of the head, the active phase is the maternal effort to push and expel the baby

53
Q

Define and describe the 3rd stage of labour

A

The time from completing birth to expulsion of the placenta and membranes. It takes around 5-15 mins, but 30-60 mins may be normal under some circumstances.

54
Q

What type of lie do you want for normal delivery?

A

longitudinal, not transverse

55
Q

What is a frank breech?

A

baby is facing bottom down (not head down) and legs and feet feet up

56
Q

What is a full/ complete breech?

A

the baby is facing bottom down with legs up but feet facing down or crossed (complete breech is with one foot facing down and one facing up)

57
Q

What is a single footed breech?

A

Where the baby is facing bottom down, with one foot in birth canal.

58
Q

How can labour be induced? (4)

A
  • Stimulate release of prostaglandins by artificial membrane rupture (use hook and break amniotic membrane yourself)
  • Give artificial prostaglandins
  • give synthetic oxytocin
  • give anti progesterone agents
59
Q

How can a foetus be monitored in child birth? (5)

A
  • measure HR
  • measure mums body temp
  • babies colour
  • amount of amniotic fluid
  • scalp capillary pH
60
Q

Describe the babies movements during birth

A
  1. it starts with whole body facing laterally
  2. The head flexes to bring it close to the chest
  3. the head and shoulders rotates internally (to face towards spine)
  4. The head crowns
  5. the head extends- in doing the head is delivered and then it rotates externally (restitution) so that the head is facing laterally again
  6. The shoulders also rotate externally again to face laterally and are delivered one at a time
  7. the rest of the baby follows easily.
61
Q

Erbs palsy can occur due to injury to the brachial plexus during shoulder delivery, what is erbs palsy?

A

there is damage to the upper roots- C5 and 6, leading to loss of innervation to the musculocutaneous, axillary, subclavius and suprascapula nerves.
This leads to loss of sensory to lateral side of arm and internal rotation of the arm, extension of the elbow and pronation of the forearm as the opposing actions are lost/ weakened.

62
Q

What other injuries can occur to the baby during delivery?

A

dislocations, broken bones, facial injuries

63
Q

How is blood loss limited after delivery?

A
  • The uterus contracts, constricting blood vessles running through the myometrium.
  • The pressure exerted on the placenta side by the walls of the contracted uterus effectively close blood vessels
  • The blood clots
64
Q

How much blood is lost on normal delivery?

A

500ml-1 L

65
Q

What is the most common cause of post partum haemorrhage?

A

Uterus atony- failure of the uterus to contract.

May also be due to bleeding disorders ect.

66
Q

Sheehans syndrome is a rare complication of shock caused by post haemorrhage, but what is it?

A

Where the anterior pituitarys blood supply isnt good enough so it dies, leading to headaches, lack of lactation, hypothyroidism, addisions, weak pulse ect

67
Q

What causes the baby to take its first breath?

A

number of stimuli:

  • trauma
  • cold
  • light
  • noise
  • reduced pulmonary resistance
68
Q

Describe the circulation changes in the baby at birth

A
  • clamping of ductus venosus (in umbelllical cord) causes blood to flow through liver
  • first breath decreases vascular flow resistance to lungs, so blood flows through pulmonary vessels
  • drop in pressure on the right side of the heart and rise in pressure on the left as pulmonary circulation starts closes the foramen ovale
  • muscle wall of the ductus arteriosus contracts to stop flow from PA to aorta
69
Q

What arteries supply the breasts?

A

internal throacic arteries, intercostal arteries, thoacolacrimal arteries, lateral thoracic arteries

70
Q

What veins drain the breasts?

A

axillary, posterior intercostal and internal thoracic veins

71
Q

What lymph nodes drain the breasts?

A

axillary and parasternal nodes

72
Q

Describe changes to the breasts during pregnancy

A

Progesterone, oestogen, prolactin and GH cause hypertrophy of alveolar ducts. They also stimulate formation of new ducts and acini (glands)

73
Q

Describe the suckling reflex

A

Suckling and other stimuli cause prolactin release which stimulated milk production. It also causes oxytocin release which stimulates contraction of myoepithelial cells around acini to cause milk release.

74
Q

Describe the composition of the colstrum produced from the breasts of the first couple of feeds

A

it has higher fat and immunoglobulin content than the milk produced on subsequent feeds

75
Q

Give 3 breast problems which may occur post partum

A
  • nipple sensitivity and pain
  • benign breast lumps common
  • engorgement as milk builds up but isnt released (painful)
  • Mastitis- celluitis of breast tissues, often blocks ducts an is painful
  • abcesses
76
Q

What is the difference between baby blues and post partum depression?

A

baby blues peaks at 3 or 4 days after delivery, affects 85% and generally isnt as severe as depression, depression occurs within 4 weeks of delivery and only affects 13% of mums

77
Q

What is the name for severe post partum depression with paranoia, restlessness, mania, delusions and anxiety?

A

puerperal pyschosis

78
Q

What is pre- eclampsia

A

High blood pressure and proteinuria in pregnancy

79
Q

Why does pre- eclampsia occur?

A

Placenta doesn’t implant properly, causing ischaemia and so inflammation. This leads to vascular endothelial dysfunction leading to hypertension (may be to compensate for poor perfusion) and hyperpermeability (leads to odema).

80
Q

What signs and symptoms may pre eclampsia present w/?

A
  • headache (severe, frontal)
  • swelling of face, neck, hands and feet
  • visual disturbances (odema in eye)
  • slower reflexes
  • epigastric pain
  • vomiting
81
Q

How can pre- eclampsia be avoided?

A

low dose aspirin and calcium supplements

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