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Stage 2: Human Deveopment > Placental Development and Physiology + Multiple Pregnancy > Flashcards

Placental Development and Physiology + Multiple Pregnancy Flashcards

1
Q

What is kind of disease is pre-eclampsia and what causes it?

A

Multi-organ disease, placenta

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2
Q

When is pre-eclampsia cured?

A

After birth

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3
Q

Why does gestational diabetes cause a large baby?

A

Bc glucose stimulates growth in baby

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4
Q

What consequence can gestational diabetes lead to?

A

Stillbirth

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5
Q

What keeps the early embryo alive?

A

Decidua

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6
Q

Describe placental morphogenesis

A

1) The placenta develops over the entire surface of the chorion and then at 16 weeks regresses to form the discoid placenta
2) Elevated levels of oxidative stress in the peripheral regions of normal pregnancies leads to villous regression and formation of the smooth chorion leavae (hyper oxygenation at the top)

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7
Q

Describe the early placenta

A

Completely envelops the embryo

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8
Q

Describe the early embryo

A

Very anoxic, surviving on only what is produced by granular cells in the early placenta

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9
Q

What can a functional MRI pick up on in a placenta?

A

Oxygen function and cervical softening

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10
Q

Describe the trophoblast plug

A

During early pregnancy the volume of the endovascular trophoblast is such that it plugs the mouths of the spiral arteries, preventing maternal blood flow into the placenta

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11
Q

What does the trophoblast plug coincide with?

A

The period of histiotrophic nutrition (diffusion, anoxic)

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12
Q

What is the histiotroph?

A

Nutritional material in spaces between the maternal and fetal tissues, derived from the maternal endometrium and the uterine glands, not from maternal blood flow

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13
Q

How thick is the maternal endometrium at 6 weeks?

A

5-6mm with highly active glands

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14
Q

What is the decidua?

A

Thick endometrium

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15
Q

Name 3 angiogenic factors active in early fetal and placental growth

A

1) VEGF = vascular endothelial factor
2) hCG = human chorionic gonadotrophin
3) hPL = human placental lactogen

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16
Q

Describe the action of progesterone in early fetal and placental growth

A

1) Progesterone stimulates glands (decidual cells) which produce prolactin
2) Prolactin stimulates glandular epithelium cells to produce the angiogenic factors, stimulating growth and proliferation of the embryo (and placenta?)

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17
Q

What are the 4 functions of the placenta?

A

1) Respiratory organ (controls gas exchange)
2) Nutrient transfer
3) Excretion of fetal waste products (like kidney)
4) Hormone synthesis

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18
Q

Describe the structure of the placenta at term

A
  • Lobules in placenta, intercepted by septum
  • Frongs contain smaller blood vessels from umbilical arteries and veins, essential for getting nutrients from mother to baby
19
Q

What is the syncytiotrophoblast?

A

Line of cells between septum and villi with umbilical vessels highly specialised for transport

20
Q

When does maternal and fetal blood come into direct contact?

A

Only at birth

21
Q

Describe the transfer of blood from mother to fetus

A

Mother’s blood comes through arteries → syncytiotrophoblast → fetal circulation

22
Q

How does maternal uterine blood flow changes with gestational age?

A

It increases greatly

23
Q

Describe cells of the syncytiotrophoblast

A
  • Syncytium (connected)
  • Large nuclei
  • No cell walls
  • Brush border like kidney and gut (transport)
24
Q

Why does the fetus still exist at a low pO2 (no more than 30) even after the initial hypoxic stage?

A

To protect from oxidative stress (more pCO2)

25
Q

Describe the placental gas exchange gradient

A

Big gradient from mother to baby

26
Q

Does maternal and fetal blood have the same or different buffer?

A

Same - placenta controls the pH of placental blood via bicarbonate buffer (acid base balance)

27
Q

What is a big reason for SGA at birth?

A

Lack of transport of amino acids due to gene problems with transporters

28
Q

Is there a net transport of amino acids to the fetus?

A

Yes

29
Q

Why in developing countries do we want to improve the nutrition of mother before she conceives?

A

To prevent fetal growth restriction (FGR) → main problem is issue with placenta e.g. anaemia and protein deficiency

30
Q

What does there need to be for implantation to happen?

A

Low oxygen tension

31
Q

What would a gap in the placenta on US suggest?

A

Bleeding

32
Q

What happens to the placenta in pre-eclampsia and FGR?

A

1) Placental villous tree has fewer branches bc of altered blood flow characteristics
2) Spiral artery remains narrowed

33
Q

What is PI on a uterine artery doppler?

A

(Vmax-Vmin)/Vmax mean

34
Q

What does increased PI increase the risk of?

A

Severe pre-eclampsia

35
Q

When is severe IUGR best predicted in low-risk patients?

A

Second trimester by an increased PI

36
Q

Can you pick up people likely to have a PE early (at 14 weeks)?

A

Yes but can’t prevent it - looks like a non-pregnant scan

37
Q

What are monozygotic twins?

A

From one egg, identical (incidence = 3:1000 deliveries)

38
Q

What are dizygotic twins?

A

Two eggs, non-identical (incidence of spontaneous dizygotic twins = 1:80)

39
Q

What are risk factors for dizygotic twins?

A

1) Peak age 35-40 years - FSH rises, biological advantage of double ovulating, more chance of at least one succeeding
2) FH
3) Previous multiple birth
4) Increased BMI
5) Parity
6) Summer and autumn conceptions
7) Smoking
8) COCP

40
Q

What are the three types of monozygotic twins (can see on US)?

A

1) Dichorionic, diamniotic - cleavage before implantation, two placentas, two amniotic sacs
2) Monochorionic, diamniotic - cleavage at day 6-8, one placenta, two amniotic sacs
3) Monochorionic, monoamniotic - cleavage after day 8, one placenta, one amniotic sac, 4%

41
Q

What causes conjoined monozygotic twins?

A

Divide of placenta happens even later

42
Q

What increases the risk of monozygotic twins?

A

IVF

43
Q

What type of twins can be dichorionic and what type can be monochorionic?

A

1) Dichorionic - can be monozygotic or dizygotic

2) Monochorionic - can only be monozygotic

44
Q

What is the most common combination for triplets?

A

Pair of monozygotic twins and a dizygotic

Stage 2: Human Deveopment (34 decks)

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