Session 8 - Pregnancy

Question 1

Answer 1

Question 2

Onw what day does the blastocyst implant into the endometrium?

Answer 2

6

Question 3

What are primary, secondary, and tertiary placental villi?

Answer 3

Primary villi – early finger like projections into trophoblast
Secondary villi – invasion of mesenchyme into core
Tertiary villi – invasion of mesenchyme core by fetal vessels

Question 4

What are the 3 pruposes of establishing a placenta

Answer 4

• Anchor the placenta – via establishment of the outermost cytotrophoblast shell
• Establish maternal blood flow within placenta
• Establish basic unit of exchange ie villi

Question 5

What is an ectopic pregnancy? What are the consequences?

Answer 5

• Implantation at site other than uterine body, commonly fallopian tube
• Can be peritoneal or ovarian
• Can rupture and cause severe haemorrhage

Question 6

What is placenta praevia? What are the consequences and how do you treat?

Answer 6

• Placenta grows below os of uterus
• Can cause haemorrhage in pregnancy
• Requires C-section delivery

Question 7

Answer 7

Question 8

What is placental insufficiency?

Answer 8

insufficient blood flow to placenta during pregnancy caused by incomplete invasion of placenta

Question 9

What is pre-eclampsia?

Answer 9

hypertension and large amount of protein in urine during pregnancy caused by incomplete invasion of placenta

Question 10

How is the endometrium prepared for implantaiton?

Answer 10

Decidualisation – provides the balancing force for the invasive force of the trophoblast:

• Stimulated by progesterone
• W/o this complications such as haemorrhage can occur

Remodelling of spiral arteries:

• Creates low resistance vascular bed
• This maintains a high flow rate required to meet fetal demand.

Question 11

What is the fetal portion and the maternal portion of the placenta made of?

Answer 11

Fetal - Formed by chorion frondsum

Maternal - Formed by decidua basalis

Question 12

Answer 12

Question 13

What is found between the chorionic and decidual plates of the placenta?

Answer 13

intervillous spaces which are filled with maternal blood

Question 14

What are cotyledons of the placenta?

Answer 14

Decidual septa formed in the decidual plate divide the placenta into compartments or cotyledons

Question 15

How does the thickness of the placenta change in the first and second trimester?

Answer 15

First trimester placenta:

• Placenta established
• Placental barrer to diffusion still thick
• Complete cytotrophoblast layer beneath syncytotrophoblast

Second trimester placenta:

• Loss of cytotrophoblast layer
• Barrier thin
• SA for exchange increased

Question 16

Where do cotyledons recieve their blood from?

Answer 16

through spiral arteries that pierce the decidual plate.

Question 17

Which substances are actively transported across the placenta? What about facilitated diffusion?

Answer 17

Active transport:

• Amino acids
• Iron
• Vitamins

Facilitated diffusion:

• Glucose

Question 18

Give 3 examples of teratogens

Answer 18

thalidomide, alcohol, smoking

Question 19

Give 2 examples of pathogens able to cross the placenta

Answer 19

Cytomegalovirus

Rubella

Question 20

Name the 4 protein and 2 steroid hormones produced by the placenta

Answer 20

Protein

• hCG
• hCS
• hCT
• hCC

Steroid:

• Progesterone
• Oestrogen

Question 21

How long is hCG produced for? What does it do?

Answer 21

• produced during first 2 months of pregnancy
• supports secretory function of corpus luteum

Question 22

What is the function of hCS?

Answer 22

influences maternal metabolism, increasing availability of glucose to fetus

Question 23

What does progesterone do during pregnancy?

Answer 23

influences maternal metabolism by increasing appetite

Question 24

What is the hormonal basis of testing for pregnancy?

Answer 24

hCG pregnancy specific and excreted in maternal urine

Question 25

How does the placenta provide passive maternal immunity to the neonate?

Answer 25

* fetal immunoglobins consist of maternal IgG which are transported from mother at approx. 14 weeks * IgG transported via receptor mediated pinocytosis

Question 26

What is haemolytic disease of the newborn? How is it treated?

Answer 26

* IgG antibodies produced by mother attacks RBCs of neonate. * Due to incompatability of rhesus blood groups between mother and fetus. * Mother prevbiously sensitised to rhesus antigen e.g. prevbious pregnancy * Treated with prophylactic treatment

Question 27

What happens to CO, BV, SV, HR, BP during pregnancy?

Answer 27

all but BP increaeses. BP decreases.

Question 28

Why is there a decrease in BP during pregnancy?

Answer 28

* T1 and T2 – progesterone effects on systemic vascular resistance * T3 – aortocaval compression by gravid uterus results in reduced return to heart. Can result in syncope when lying in supine position. Roll woman on left to relieve compression.

Question 29

What happens to renal plasma flow, GFR, Creatinine clearance, protein excretion, plasma urea, plasma uric acid, plasma bicarbonate during pregnancy?

Answer 29

Plasma urea, uric acid, and bicarbonate decrease Rest increases

Question 30

Why can urinary stasis occur during pregnancy? What are the possible consequences of this?

Answer 30

Progesterone relaxes smooth muscle of ureter which can result in stasis, hydroureter, UTIs, and pyelonephritis (PN can induce pre-term labour)

Question 31

Why does the mother go into physiological hyperventilation? How does this occur? What happens to plasma pH and how do the kidneys compensate?

Answer 31

* Pregnancy results in physiological hyperventilation driven by progesterone so mother can blow off extra CO2 produced by fetus: * Leads to resp alkalosis, which kidneys compensate for by producing and reabsorbing less bicarbonate

Question 32

How does the metabolism of carbohydrates change for the mother? How do the hormones help do this?

Answer 32

* Progesterone stimulates appetite in first half of pregnancy and diverts glucose into fat synthesis * Oestrogen stimulates increase in prolactin release, generates maternal resistance to insulin * Maternal glucose usage thus declines and gluconeogenesis increases, maximising availability of glucose to fetus * Later in pregnancy, mother’s energy needs are met by metabolising peripheral fatty acids

Question 33

What is gestational diabetes? What are the risks associated with it?

Answer 33

Carb intolerance first recognised in pregnancy and does not persist after delivery Risks associated with poor control: * Macrosomic getus * Stillbirth * Increased risk of congenital defects

Question 34

How does the insulin production change as pregnancy proceeds? Why do some women develop gestational diabetes as a result?

Answer 34

* Rate of secretion of insulin increases as pregnancy proceeds * Achieved by beta cell hyperplasia and hypertrophy and increased rate of insulin synthesis in beta cell * In some women, endocrine pancreas unable to respond to metabolic demand of pregnancy and cannot release enough insulin, results in loss of control of metabolism, blood glucose increases and diabetes results

Question 35

How does plasma conc of FFAs change during pregnancy and why?

Answer 35

Increase in plasma conc of FFAs during fasting for mother to use, sparing glucose for fetus

Question 36

How does levels of T3 and T4 change and why?

Answer 36

* Thyroid binding globuilin production increased * Therefore T3 and T4 increased * BUT free T4 still in normal range

Question 37

How does the smooth muscle relaxation of the GI system impact it?

Answer 37

* Delayed emptying of GI * Biliary tract stasis * Increased risk of pancreatitis

Question 38

Why does a physiological anaemia develop during pregnancy?

Answer 38

* Plasma volume increases * RBC mass also increases * Physiological anaemia results – due to mismatch between volume and haemocrit

Question 39

What is an allograft?

Answer 39

Genetically different, same species

Question 40

What are the hallmark features of pre-eclampsia and how does this compare to a normal pregnancy?

Answer 40

Normal pregnancy: * Vasodilated * Plasma expanded Pre-eclamptic pregnancy: * Vasoconstricted * Plasma contracted * Raised blood pressure * Proteinuria * Pitting oedema

Question 41

What hormone can be used to measure fetal progress?

Answer 41

estriol. Low levels can indicate fetal distress

Question 42

How much is cardiac output increased by in pregnant women?

Answer 42

40%

Question 43

How much is HR increased by in pregnant women?

Answer 43

to 80/90

Question 44

How much is o2 consumption increased by in pregnant women?

Answer 44

15%

Question 45

How much is tidal volume increased by in pregnant women?

Answer 45

40%

Question 46

What is reflex hypoglycaemia in a child?

Answer 46

If uncontrolled maternal diabetes occurs, foetus increases secretion of insulin. Once isolated from other, neonate experiences reflex due to hgih circulating levels of insulin, can damage brain due to hypoglycaemia.