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Reproduction, Development and Ageing > 3. Pregnancy + labour > Flashcards

3. Pregnancy + labour Flashcards

1
Q

Which trimester are spontaneous miscarriages more likely in?

A

First trimester

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2
Q

What is the absolute limit survival outside the womb, without the intensive care unit?

A

27 weeks

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3
Q

What factor defines the end of the 2nd trimester?

A

Absolute limit of survival outside the womb (end of 27 weeks)

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4
Q

What happens to maternal blood volume, blood clotting tendency and blood pressure during pregnancy?

A
  • Blood volume - increased
  • Blood clotting tendency - increased
  • Blood pressure - decreased

(all in 2nd trimester)

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5
Q

In which trimester is matenral brain function, hormones, immune system, appetite and emotional state altered?

A

1st trimester

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6
Q

What functional homologue of LH (driving oestrogens and progesterones production) is the key hormone of human pregnancy?

A

Human chorionic gonadotrophin

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7
Q

Where does hCG stimulate progesterone production from to keep the pregnancy going?

A

Corpus luteum

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8
Q

Which somatotrophin hormone increases as the size of the placenta increases?

A

Placental lactogen (oestrogens and progesterones show the shame pattern)

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9
Q

Which organ takes over oestrogen/progesterone production from the corpus luteum a few months into pregnancy?

A

Placenta

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10
Q

In which trimester are there peak hCG levels?

A

1st trimester (then declines after)

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11
Q

What happens to LH and FSH during pregnancy?

A

Suppressed by steroids negative feedback on HPG

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12
Q

Which part of pregnancy poses the biggest threat to maternal health and life?

A

Delivery process

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13
Q

What is a conceptus?

A

Everything resulting from ferilised egg (baby, placenta, umbilical cord etc.)

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14
Q

What is the expected timing of delivery?

A
  • 39-40 weeks

* 280 days since the beginning of the last menstrual period

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15
Q

When do we establish ovulation, and what do embryologists use as the point of fertilisation?

A
  • We take first day of the last menstrual period, and work out ovulation as 2 weeks after that day
  • Embryologists take the first day as the point of fertilisation

2 week difference, but not huge difference in the scheme of term dates

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16
Q

Which gestational ages does ‘term’ cover?

A

37-41 weeks gestation

Any deliveries either side of these limits are pre-term or post-term

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17
Q

What are agents that can harm the development of an embryo or foetus?

A

Teratogen (more vulnerable earlier on in pregnancy)

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18
Q

What are the separations in the placenta called?

A

Cotyledons (30-60 per placenta)

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19
Q

What is the primary subunit of the placenta?

A

Placental villus

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20
Q

Describe the development of the human placenta?

A
  • Conceptus is almost completely implanted within the endometrium (day 9 post-fertilisation)
  • Outer layer is multinucletated syncytiotrophoblasts, containing fluid-filled lacunae
  • Underlying cytotrophoblast is proliferating into the syncytium
  • Columnar structure forms (cytotrophoblast column) which undergoes branching (villous sprouts)
  • Mesenchymal cells at the centre of each villus - villus vascular system develops from these cells
  • Branching continues
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21
Q

Why are there fewer cytrotrophoblasts at term?

A

For closer apposition between the syncytium and placental capillaries

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22
Q

Explain the remodelling of arteries in the placenta?

A

• Cytotrophoblast cells block spiral arteries - part of remodelling them
- limited oxygen supply could keep free radicals low
• Also involves loss of endothelium and smooth muscle cells of the arteries
• End up with distended, non-vasoactive vessels - can carry more blood at low pressure
• Allows high blood supply in trimesters 2 and 3 (greatest growth)

23
Q

What does the cytotrophoblast do to the conceptus for 4 week post-fertilisation?

A
  • Forms a shell around the conceptus
  • Isolates it from maternal blood
  • Shell remains in place for 8 weeks, plugging the spiral arteries
  • Breaks down during week 10-12 starting with those at periphery of placenta
24
Q

What initally provides the nutrients to the placenta and developing baby?

A

Decidual glands (hypertrophy)

25
Q

What can happen if the placenta isn’t fully anchored to the maternal decidua?

A

Increased pressure from arterial supply can detatch it => miscarriage

26
Q

What percentage of pregnancies end in labour (including emergency Caesarean), or are delivered by electrive Caesarean?

A
  • Labour - 75%

* Caesarean - 25%

27
Q

What should a newborn baby look like?

A
  • Soaking wet
  • Tension in its limbs
  • Air bubble at the mouth (indicates crying)
  • Head and body are the size of an adult hand and forearm respectively
28
Q

What is a breach?

A

The baby is the wrong way up

29
Q

What happens to the foetal membranes during labour?

A
  • Remodelled

* More likely to rupture

30
Q

What are Braxton Hicks contractions?

A
  • Part of the myometrium contracts briefly, then relaxes
  • Occurs intermittently, but regularly
  • Last 8 weeks of pregnancy
31
Q

What happens in Phase I of labour?

A
  • Can last many hours
  • Fundally dominant contractions
  • Cervical ripening (softening) and effacement (thinner)
  • Varies from 12-48 hours
32
Q

What happens in Phase II of labour?

A
  • Can last hours

* Baby is delivered in this phase

33
Q

What happens in Phase III of labour?

A
  • Half an hour (approx.)

* Placenta is delivered in this phase

34
Q

How does the length of labour change with time?

A
  • Gets shorter

* Uterus might get better at changing

35
Q

What causes labour?

A
  • Not really known

* Could by driven by oestrogens, low progesterone or CRH (corticotrophin-releasing hormone) and oxytocin

36
Q

What can cause pre-term labour?

A
  • Intrauterine infection (or elsewhere
  • Intrauterine bleeding
  • Multiple pregnancy
  • Maternal stress
37
Q

What does cervical ripening and effacement involve?

A 
• Loss of ECM
• Recruitment of leukocytes (neutrophils)
• Inflammatory, production of:
- prostaglandin E2, IL-8
• Local (paracrine) change in IL-8
38
Q

What mediators does the myometrium become more responsive to, to make it contract in labour?

A
  • Prostaglandin E2 (levels increase)
  • Oxytocin receptor increased
  • Contraction associated proteins
39
Q

What contributes to the rupture of foetal membranes in labour?

A
  • Loss of strength due to changes in amnion basement component
  • Inflammatory changes - leukocyte recruitment
  • PGs, interleukins
  • Increased levels and activity of matrix metalloproteinases
40
Q

Which key transcription factor switches on many processes in labour?

A

NF-kappa-B (NFkB)
• Part of the classic pro-inflammator cascade
• Enters the nucleus to upregulate a range of protiens e.g. cytokines, chemokines, adhesion molecules and COX-2

41
Q

Which cytokine is an example of why labour is so difficult to stop once it’s started?

A

IL-1 can uprefulate the NFkB pathway further - positive feed-forward loop

42
Q

Can foetal membranes influence PGE2 production (the ones that induce labour)?

A

Yes

43
Q

How does the CRH binding protein change in labour?

A

Declines => increased free CRH

44
Q

How does platelet activating factor (PAF) affect the pro-inflammatory cytokines involved in labour?

A

Upregulates them - could be part of labour control

45
Q

How does PAF affect the lungs?

A
  • Part of lung surfactant
  • Increase of PAF could be for baby surfactant, as they don’t have it in utero (all O2 from placenta)
  • Surfactant proteins and complexes are produced in the last months of pregnancy (increase in amniotic fluid)
  • This is a foetal sign of maturity (lungs are the last thing to develop in a baby)
46
Q

Where is CRH produced in pregnancy?

A

Placenta

47
Q

Which hormone stimulates lung development and how does it affect CRH?

A
  • Cortisol
  • Stimulates PAF (production and) to enter the amniotic fluid, which is taken up by baby into lungs
  • Normally it switches down CRH production
  • In the placenta, it switches up CRH production
  • Causes the rapid rise of CRH in the last few weeks of pregnancy
48
Q

What is DHEAS and what does it do in labour?

A
  • Steroid produced in the adrenal glands
  • Can move to the placenta and be converted to oestrogens
  • Oestrogens upregulate PGs, oxytocin and oxytocin receptors
49
Q

Why might multiple pregnancies cause pre-term labour?

A
  • Multiple placentae
  • More CRH
  • Accelerated labour
  • Also more stretch of the uterus
50
Q

Which hormone is needed to sustain pregnancy?

A

Progesterone

progesterone antagonist can cause pregnancy loss

51
Q

What happens to the effect of progesterone in labour?

A
  • Lost

* Interaction between the progesterone receptor and NFkB

52
Q

Why does NFkB not upregulate inflammatory cascades for most of pregnancy?

A
  • Lots of progesterone receptors

* NFkB interact with them, so they cannot do their normal job

53
Q

Describe the 2 sorts of progesterone receptors and how they change at term

A
  • PR-A and PR-B
  • PR-B is more active and mediates the main effects of progesterone via gene expression
  • PR-A is less able to mediate these effects
  • Ratio of PR-A:PR-B increases at term
  • Causes progesterone to have less of an effect - allows labour to take place

Reproduction, Development and Ageing (7 decks)

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